Improve the testing guide [ci skip]

Improve the "Testing Rails Applications" guide adding a section for
testing helpers and a little note about associations with ActiveRecord
and YAML fixtures.

Also add a link to Fixture Builder ; yet another replacement for
fixtures such as Machinist or FactoryGirl.
Remove conditional, since results are always an instance of `ActiveRecord::Result`
Added SanitizeHelper to rails guide docs [ci skip]

Added SanitizeHelper to rails guide docs [ci skip]

Added SanitizeHelper to rails guide docs update [ci skip]
Creating an SSE class to be used with ActionController::Live.
Added Action View in 'rake about' [ci skip]
Add tmp dir in actionview/test/

Missing tmp directory will cause the test to fail on JRuby. will commit
adds tmp directory & 22 TemplateDigestorTests which were failing before
are now green.

Further Discussion on this can be seen at #11743
load fixtures from linked folders
Merge pull request #11767 from kassio/master-load-fixtures-from-linked-folder

Load fixtures from linked folders[master]
Use the right instrumentation name

The pattern is event.component

Closes #11769

Conflicts:
	railties/CHANGELOG.md
Remove deprecated branch on the scope method.

The deprecation message was removed on 50cbc03d18c5984347965a94027879623fc44cce but the code was not.
config[:database] should be a string

This change was breaking the Railties tests. See
https://travis-ci.org/rails/rails/jobs/9865969
Merge pull request #11743 from gaurish/tmp-magic

[Jruby] Make all tests in ActionView::TemplateDigestorTest green
Remove privatizing of Fixnum#/ from assert_distance_of_time_in_words

MRI reimplemented Date in C so it doesn't hit this division anymore
while JRuby still uses the old stdlib implementation of Date so
it will always hit this.

With this change the actionview date_helper_test.rb tests should pass on JRuby.
Merge pull request #11771 from atambo/jruby_assert_distance_of_time_in_words

Remove privatizing of Fixnum#/ from assert_distance_of_time_in_words
added String#to_date documentation to Rails 4 upgrade guide

[ci skip]
#11759: Update Assets Pipeline Guide

by default included to precompile only non-js/css files from `app/assets` and `application.(css|js)`
adding a weird test case
Merge pull request #11778 from jetthoughts/11759_update_assets_guides

Update Assets Pipeline Guide [ci skip]
Add CHANGELOG entry for #11767

[ci skip]
asakusa.rb hack night!

Fix in-memory tests