Propagate test messages through assert_routing helper, Fixes #14908

assert_routing was not raising the message passed into the assertion
violation that it raised. This change propagates messages through
the on_fail error.

This fixes this error:
https://github.com/rails/rails/issues/14908

A test case for this issue is located here.
https://github.com/estsauver/test14908

To see that test case fail in the example app, just run
ruby -Itest test/controllers/guests_controller_test.rb
reset_column_infomation shouldn't be part of the assertion.
Preparing for 4.2.0.beta1 release
provide a builder for form labels to customize wrapping around I18n content
Cache the value of `changed_attributes` when calling `changes_applied`

`changes_applied` calles `changes`, which will call `changed_attributes`
multiple times in a loop. This method actually performs work now, so we
should cache the results while looping over it when we know it cannot
change.
Use system /tmp when testing actionpack

https://github.com/rails/rails/commit/c64bff2c87ebf363703c63ecd4a96d56a1a78364
added support and enabled parallel execution of the actionpack tests.

However it introduced https://github.com/rails/rails/commit/c64bff2c87ebf363703c63ecd4a96d56a1a78364
since one cannot connect to a socket file that's inside a Vagrant synced folder
due to security restrictions, and DRb tries to.

Also rename the temporary files to make it obvious that they're rails-related,
since now they're placed outside the project's directory.

Fixes https://github.com/rails/rails/commit/c64bff2c87ebf363703c63ecd4a96d56a1a78364
Update documentation to match change in #5942 [ci skip]
recount files quantity
[ci skip ]Document transform_values && transform_values!
[ci skip] document truncate_words
code quotes for classname
[ci skip] wrap to 80 chars
[ci skip] docs asset_pipeline#CDNs
[ci skip] docs asset_pipeline CDN set up
[ci skip] docs CDN caching behavior
[ci skip] docs CDN header debugging
[ci skip] docs CDN Cache-Control behavior
[ci skip] docs can URL cache invalidation
Don't ignore constraints in redirect routes

https://github.com/rails/rails/commit/402c2af55053c2f29319091ad21fd6fa6b90ee89
introduced a regression that caused any constraints added to redirect routes
to be ignored.

Fixes #16605
[ci skip] fix grammar in docs