Add rake test description

No behavior change
Fix #9360 regression in content_for
cache_key consults updated_on timestamp if present

- Extract max timestamp retrieval for cache_key
- Update changelog for cache_key changes
update docs, change_table does not use TableDefinition.
Support PostgreSQL specific column types when using `change_table`.

Closes #9480.

We use `TableDefinition` for `#create_table` and `Table` for `#change_table`.
The PostgreSQL sepcifc types were only defined on `TableDefinition` so I
also added them to `Table`.
Merge pull request #9484 from senny/9480_change_table_and_hstore

Support PostgreSQL specific column types when using `change_table`.

We use `TableDefinition` for `#create_table` and `Table` for `#change_table`.
The PostgreSQL sepcific types were only defined on `TableDefinition` so they needed to be added to `Table` as well.
Wrong exception is occured when raising no translatable exception
Ensure plugins generated with plugin new can boot the dummy application
Document introduction of the ActionController::UnknownFormat exception
Document extraction of actionpack-xml_parser
Improve docs for UpgradeSignatureToEncryptionCookieStore
Document the switch from memcache-client to dalli
Document rails-observers extraction
Document caveat from 5b3bb61 which fixed handling SCRIPT_NAME from within mounted engine
Merge pull request #9366 from killthekitten/fix-content_for-regression

Fix for #9360 content_for regression
Document sass-rails asset_url deprecation
Improve the CHANGELOG entry

[ci skip]
Merge pull request #9493 from kennyj/fix_wrong_exception

Wrong exception is occured when raising no translatable exception

Closes #8617
Document removal of assets:precompile:primary
Improve the CHANGELOG entry

[ci skip]