Fixed API task file

1. As we have vendor in AV only
2. No more vendor in AC
3. No vendor folder in AR
grab executable from rubygems
Fix order dependent test

see c48cbb02d7e6f585e31b404c0c363f0d6b586811
Back AV description in gemspec
Remove helper fixtures not used in any test

The fixture for module AbcHelper defines three functions bare_a,
bare_b and bare_c, but only bare_a is used in the code that tests
helper functions.
stop using deprecated api in the tests
make @bitsweat happy. :heart:
let the class cache object clean up user input
Merge pull request #12181 from claudiob/remove-unused-helper-fixtures

Remove helper fixtures not used in any test
Removed unnecessary require
Removed unused modules and classes
Merge pull request #12187 from anupamc/master

Removed unnecessary require
use assert_empty in activemodel conditional validation test cases
Make AC standalone rendering work
Merge pull request #12173 from arunagw/fixes_reverted_by_revert_commit

Revert fixes
Merge pull request #12189 from rajcybage/test_assert

use assert_empty in activemodel conditional validation test cases
Don't mutate the Base settings by merge!ing the given value
Refactor handling of action normalization

Reference:
Bloody mess internals
http://gusiev.com/slides/rails_contribution/static/#40
Reset ActionView::Base.logger instead of AC::Base.logger

see: 9b0ac0bc74569db460f87ea6888b3847be0ff5be
Clean up unused associations in AR test model