Removed the unused require of proxy_object

- Reference : https://github.com/rails/rails/pull/17493#issuecomment-61739359
- Duration stopped inheriting from ProxyObject in https://github.com/rails/rails/pull/16574

Fix broken string_ext_test due to change in timezone

- Russian time was changed to UTC+3 from UTC+4 recently. This broke the
  string_to_ext test.

[ci skip] fix `config.assets.digest` default value

Fixup spelling and grammar in 4.2 guides

Capitalize CSS, SQL

Change spelling of favour to favor - updated for consistency,
the rest of the document uses "favor".

Grammar / spelling pass

* 17106:
  add lib to $LOAD_PATH on application inhertence. fixes #17106
  add a test for #17106

Mention that articles resource should be added by user in getting started guide

Fixes #17507 [ci skip]

[ci skip]

Added SchemaDumper support for tables with jsonb columns

Move DebugExceptions#traces_from_wrapper to ExceptionWrapper

update rails version for earlier releases in edgeguides [ci skip]

minor docs change [ci skip]

added example for hash slice method [ci skip]

From dc5854f3 and c07c0b26 [ci skip]

for serialization and deserialization of jobs. [ci skip]

Remove redundant `to_s` in interpolation

Change `rails` to `bin/rails` in getting started, fix #1748 [ci skip]

ActionDispatch::ExceptionWrapper seems to be the more natural place for
this method to live in.

Avoid unnecessary allocations and method calls

Make `String#remove` and `String#remove!` accept multiple arguments

Conflicts:
	activesupport/CHANGELOG.md