Fixes #18473

bebugger doesn't work with Ruby 2.2 so we don't need to support it
anymore

This stems from [a comment](rails#17227 (comment)) by @dhh.
In summary:

* New Rails 5.0 apps will not accept `return false` as a way to halt callback chains, and will not display a deprecation warning.
* Existing apps ported to Rails 5.0 will still accept `return false` as a way to halt callback chains, albeit with a deprecation warning.

For this purpose, this commit introduces a Rails configuration option:

```ruby
config.active_support.halt_callback_chains_on_return_false
```

For new Rails 5.0 apps, this option will be set to `false` by a new initializer
`config/initializers/callback_terminator.rb`:

```ruby
Rails.application.config.active_support.halt_callback_chains_on_return_false = false
```

For existing apps ported to Rails 5.0, the initializers above will not exist.
Even running `rake rails:update` will not create this initializer.

Since the default value of `halt_callback_chains_on_return_false` is set to
`true`, these apps will still accept `return true` as a way to halt callback
chains, displaying a deprecation warning.

Developers will be able to switch to the new behavior (and stop the warning)
by manually adding the line above to their `config/application.rb`.

A gist with the suggested release notes to add to Rails 5.0 after this
commit is available at https://gist.github.com/claudiob/614c59409fb7d11f2931

The changes in #18149 added tests for the app generator, but only fixed
it for the plugin generator (I should have let CI finish though I think
it would have failed as an allowed failure).

https://travis-ci.org/rails/rails/jobs/39190983#L460

 1) Failure:
 AppGeneratorTest#test_psych_gem
 [test/generators/app_generator_test.rb:495]:
 Expected /gem 'psych',\s+'~> 2.0', \s+platforms: :rbx/ to match <snip>
 http://git.io/uuLVag)\ngem 'psych', '~> 2.0', platforms: :rbx\n\n

For the most part of cases --skip-gems option just remove one line in
the Gemfile. This is not worth for the complexity it adds.

Closes #17196

Change position of require active_job

Broken by fbe38c9e

The template runs before the generation of binstubs – this does not
allow to write one, that makes an initial commit to version control.
It is solvable by adding an after_bundle callback.

Since the rubysl-yaml gem doesn't ship with Psych by default because of
its dependency on libyaml, on Rubinius, the default engine is Syck.

However, if we want to be able to run the application safely on
different rubies, we need to make people using Rubinius rely on Psych.

See http://git.io/uuLVag for further information.

We are planning to remove mocha from our test suite because of
performance problems. To make this possible we should stop require mocha
on ActionSupport::TestCase.

This should not affect applications since users still need to add mocha
to Gemfile and this already load mocha.

Added FIXME notes to place that still need mocha removal

Also remove --skip-turbolinks.

This option is useful if users want to remove some gems like jbuilder,
turbolinks, coffee-rails, etc that don't have specific options on the
generator.

    rails new my_app --skip-gems turbolinks coffee-rails

The fix introduced at 75ba7425 were
missing this case.

To fix the original issue mentioned at that commit the correct is to
remove update_config_files from the command list since we should not run
both config_files command when creating a new application.

Tests were added to make sure everything is working fine.

sprockets-rails 2.1 needs the precompile list to be available in all
environments.

If the sqlite file name change in future version we this regexp should
catch

From #14026:

    Specific rbx-2 to limit testing on Rubinius 2.x (since there will be
    other versions of Rubinius > 2.x soon).

    Also, as of Rubinius 2.2.5, it is no longer necessary to bundle the
    rubysl gem.

This is what Rails master/4.1 supports, so we don't need to add rubysl to
gemfiles anymore.

Squashed commit of the following:

commit 96991e8e919edfb20cc4120bca4e36ed51175d57
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:29:24 2014 -0800

    Revert "gems can be added or skipped from the template"

    This reverts commit 8beb42cf.

    Conflicts:
    	railties/lib/rails/generators/rails/app/app_generator.rb
    	railties/test/generators/app_generator_test.rb

commit 35599c0e657245ef14ac0f28c9189ad16acf40e6
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:26:53 2014 -0800

    Revert "oops, template replay needs to happen after bundle. :orz:"

    This reverts commit 9104702b.

    Conflicts:
    	railties/lib/rails/generators/rails/app/app_generator.rb

commit f519c3902c313db8e906a49251c91643b8e6499e
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:51 2014 -0800

    Revert "only ask for these ivars if the target responds to them"

    This reverts commit 656d4125.

commit aa524a9428e3e4c45fe221f10a66a08efb827ab5
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:39 2014 -0800

    Revert "refactor generator tests to use block form of Tempfile"

    This reverts commit 65251820.

commit 7d3740549fa4dfa62e3761f8d4bc6d6d441256e7
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:25 2014 -0800

    Revert "add a more restricted codepath for templates fixes #13390"

    This reverts commit 2875b4a6.

commit 525df0af1001918986cdfce59539fd2d52c4f32c
Author: Aaron Patterson <aaron.patterson@gmail.com>
Date:   Fri Feb 14 11:25:11 2014 -0800

    Revert "add a send so `apply` can be called.  Fixes #13510"

    This reverts commit c5034d60.

Rename allowed options to :marshal and :json, for custom serializers
only allow the use of custom classes.

MessageEncryptor has :serializer option, where any serializer object can
be passed. This commit make it possible to set this serializer from configuration
level.

There are predefined serializers (:marshal_serializer, :json_serialzier)
and custom serializer can be passed as String, Symbol (camelized and
constantized in ActionDispatch::Session namepspace) or serializer object.

Default :json_serializer was also added to generators to provide secure
defalt.

This Adds helpers(jruby_skip & rbx_skip). In Future, Plan is to use
these helpers instead of calls directly to
RUBY_ENGINE/RbConfig/JRUBY_VERSION

Spring makes extensive use of Process.fork, so won't be able to provide
JRuby Support, hence skip these tests on JRuby.

Kudos to @zzak for taking over SDoc and make it work with RDoc 4.