Defines the return type of select / select_all method.
Added some usage about ActiveRecord::Result [ci skip]
Merge pull request #11461 from kennyj/fix_11454

Fixes #11454 . We should define the return type of select_all method clearly.
Fix changelog syntax and use Ruby 1.9 hash style [ci skip]
Use merge! to avoid a new hash and change some spots to 1.9 hash style
Leave the knowledge of boolean tag values to content tag

content tag already knows which tags are boolean and the values that
should generate them when a truthy value is passed, so leave this logic
for it instead of duplicating when generating options tags.
Uses mysql2 0.3.13 or later
Merge pull request #11558 from kennyj/bump_mysql2_to_0_3_13

Uses mysql2 0.3.13 or later.
decouple extensions from association object state
extend by adding relationships rather than monkey patching
only flatten one side
remove unnecessary reader
AR::Base does not need to know how to create reflection objects
Stop reading the same file twice for testing different content

assert_file already gives this functionality for free by passing
multiple contents.
use the predicate method