Improve redundancy in line tasks

* [ci skip] Update links in RDOC_MAIN and remove style of word rails in README

* [ci skip] Update links in RDOC_MAIN and remove style of word rails in README

[Felipe Tovar & Rafael Mendonça França]

Fixes StrongParameters `permit!` to work with nested arrays

Add RuboCop for `assert_not` over `assert !`

Add exculude condition in rubocop.yml

Navigate edgeguides from .github template [ci skip]

Similarly to https://github.com/rails/rails/pull/32626/commits/9c3fe52f5fa9904b43bf76be13f85db57c223d0c

[ci skip] Update README and RDOC_MAIN

* Navigate prefer edgeguide over guide
* Because edgeguide is always described latest policy we have

* Excluded `railties/test/fixtures/tmp/**/*` from rubocop inspect files
* These files are generated after running test in railties

Update CoC to change a history of updates URL [ci skip]

* Remove needless concat from actionpack/Rakefile
* Remove neesless File.join from actionview/Rakefile

A history of updates suggested archived URL, so changed new one:

* [NEW] https://github.com/rails/homepage/commits/master/conduct.html
* [OLD] https://github.com/rails/rails.github.com/commits/master/conduct/index.html

[ci skip] Fix minor system testing documentation typo.

Make the master.key readable only by the owner

This autocorrects the violations after adding a custom cop in
3305c78dcd.

We added `assert_not` in f75addd0 "to replace warty 'assert !foo'".
fa8d35b4 agrees that it is warty, and so do I. This custom Rubocop rule
turns the wart into a violation.

As with my last custom cop, https://github.com/rails/rails/pull/32441,
I want to make sure this looks right on code climate before pushing
another commit to autocorrect everything.

@toshimaru I just noticed
https://github.com/toshimaru/rubocop-rails/pull/26
Is there a better way to add these custom cops, or were you saying we
shouldn't have custom cops at all?

This change may only apply to POSIX-compliant systems.

Previously:

    $ ls -l config/master.key
    -rw-r--r--   1 owner  group      32 Jan 1 00:00 master.key

Now:

    $ ls -l config/master.key
    -rw-------   1 owner  group      32 Jan 1 00:00 master.key

Fix reference to fixed issue in actionpack/CHANGELOG.md

[ci skip]

Pull Request #32602 fixes Issue #32597.

[ci skip]

Fix exception in AS::Timezone.all when any tzinfo data is missing

Fixes #32610. Closes #32614.

Lua scripts in redis are *blocking*, meaning that no other client can
execute any commands while the script is running. See
https://redis.io/commands/eval#atomicity-of-scripts.

This results in the following exceptions once the number of keys is
sufficiently large:

    BUSY Redis is busy running a script.
    You can only call SCRIPT KILL or SHUTDOWN NOSAVE.

This commit replaces the lua-based implementation with one that uses
`SCAN` and `DEL` in batches. This doesn't block the server.

The primary limitation of `SCAN`, i.e. potential duplicate keys, is of
no consequence here, because `DEL` ignores keys that do not exist.

Before this change missing timezone data for any of the time zones
defined in `ActiveSupport::Timezone::MAPPING` caused a `comparison of
NilClass with ActiveSupport::TimeZone failed` exception.

Attempting to get a timezone by passing a number/duration to `[]` or
calling `all` directly will try to sort sort the values of `zones_map`.
Those values are initialized by the return value of `create(zonename)`
which returns `nil` if `TZInfo` is unable to find the timezone
information.

In our case the exception was triggered by an outdated tzdata package
which did not include information for the "recently" added time zones.

Before 078421ba `zones_map` only
returned the information that have been loaded into `@lazy_zone_map`
which ignored time zones for which the data could not be loaded, this
change restores the previous behaviour.

Add the `nonce: true` option for `javascript_include_tag` helper.

Only create an array with default options if we have default options

Output only one nonce in CSP header per request

Update validates_inclusion_of example in Docs

[ci skip]

Ruby 2.6 warning: passing splat keyword arguments as a single Hash

Before:

```
$ ruby -v
ruby 2.6.0dev (2018-04-04 trunk 63085) [x86_64-linux]

$ bundle exec rake test:template
...
/rails/actionview/lib/action_view/digestor.rb:76: warning: passing splat keyword arguments as a single Hash to `find_all'
```