Update the filestore documentation for clear
[ci skip]
Add documentation for #clear on certain Store classes
[ci skip
Add documentation for FileStore#increment and #decrement
[ci skip]
Array#to_formatted_s does not call each element's to_s anymore

Array#to_s calls each element's inspect since ruby 1.9
Remove ambiguity with pluralizations and I18n keys used for association restrict_dependent_destroy errors
Using ruby 1.9 syntax [ci skip]
Rack Sendfile is coming as default now
No need to add config for x_sendfile_header

Rack::Sendfile is loaded by default now
Added CheckPending middleware in default

As this middleware comes by default in a new
rails app

Added test to check omit for CheckPending when

Active Record is not included.
Added Rack::Sendfile in rake about [ci skip]
Merge pull request #11448 from arunagw/updated_middleware_test

No need to add config for x_sendfile_header
Remove deprecation warning from attribute_missing 

for attributes that are columns.
Merge pull request #11282 from arunagw/deprecation-removed-attribute-missing-activerecord

Remove deprecated `attribute_missing`.
Do not re-save destroyed association on saving parent object

Closes #11450
Merge pull request #11451 from jetthoughts/11450_do_not_resave_destroyed_association

Do not re-save destroyed association on saving parent object
use arel rather than slapping together SQL strings
reorder bind parameters when merging relations
removing useless assingment
save another array allocation
Lock mysql2 version to 0.3.11 since 0.3.12 is failing right now. Check #11457 for details