ConnectionPool wait_timeout no longer used for different types of timeouts. #6441

Adding deep versions of stringify_keys and symbolize_keys (plain and bang) for nested hashes

An AR ConnectionSpec `wait_timeout` is pre-patch used for three
different things:

* mysql2 uses it for MySQL's own wait_timeout (how long MySQL
  should allow an idle connection before closing it), and
  defaults to 2592000 seconds.
* ConnectionPool uses it for "number of seconds to block and
  wait for a connection before giving up and raising a timeout error",
  default 5 seconds.
* ConnectionPool uses it for the Reaper, for deciding if a 'dead'
  connection can be reaped. Default 5 seconds.

Previously, if you want to change these from defaults, you need
to change them all together. This is problematic _especially_
for the mysql2/ConnectionPool conflict, you will generally _not_
want them to be the same, as evidenced by their wildly different
defaults. This has caused real problems for people #6441 #2894

But as long as we're changing this, forcing renaming the
ConnectionPool key to be more specific, it made sense
to seperate the two ConnectionPool uses too -- these two
types of ConnectionPool timeouts ought to be able to be
changed independently, you won't neccesarily want them
to be the same, even though the defaults are (currently)
the same.

Add Hash#transform_keys and Hash#transform_keys!

Change xml type datetime to dateTime

XmlMini define the xml 'datatime', but according to
http://www.w3.org/TR/xmlschema-2/#dateTime could be better
change this to 'dateTime' with upper case letter 'T.
So 'DateTime' and 'Time' are redefined from 'datetime' to 'dateTime'

add the changing to the changelog

Remove unnecessary comment.

Added session.keys and session.values back to ActionDispatch::Request::Session

Refactor date related input helpers

These tests check the values of 'min' and 'max' input attrs

Add HTML5 color and date/time inputs

Fixed typo new_defautls -> new_defaults.

* Added tests for 'else' case in ActionView::Helpers::TranslationHelper#wrap_translate_defaults
* Also updated the testing syntax of translation.html_safe? asserts to provide better output upon failure.

This reverts commit d2901f0f, reversing
changes made to 525839fd.

Conflicts:
	activerecord/test/cases/connection_pool_test.rb

Reason: This change broke the build (http://travis-ci.org/#!/rails/rails/builds/1391490)
and we don't have any solution until now. I asked the author to try to
fix it and open a new pull request.

Move root method at TOP of routes file

Support migrating from Hash to HashWithIndifferentAccess for accessing attributes.

Made the change as per the following text in routing guide:-
"You should put the root route at the top of the file,
because it is the most popular route and should be matched first."

However, if root is best left at bottom. We will change to fix that text

In order to make migration from 3.x apps easier, we should try to
convert
Hash instances to HashWithIndifferentAccess, to allow accessing values
with both symbol and a string. This is follow up to changes in 3c0bf043.

refactor lazy_load_hooks load position, fix #6435

Use new hash syntax for generators gem method

The Gemfile of new application uses ruby 1.9 hashes. Gem method of
generators should use them too. It prevents from mixing two kinds of
syntax in one file.

remove useless require

Using require in development mode will prevent required files from
reloading, even if they're changed. In order to keep namespaced
application_controller reloadable, we need to use require_dependency
instead of require.

Rails db console improvements

Ruby tries to use '-h' as short version of '--header' by default
https://github.com/ruby/ruby/blob/trunk/lib/optparse.rb#L1372-1381.
To force `rails db -h` prints an usage message we should add the `-h`
options explicitly.

Rails uses sqlit3 db file with a path relative to the rails root. It
allows to execute server not from rails root only. For example you
can fire `./spec/dummy/script/rails s` to start dummy application
server if you develop some engine gem.

Now the `rails db` command uses relative paths also and you can explore
your dummy db via `./spec/dummy/script/rails db` command.