Merge branch 'hotfix/2.15.1'

* hotfix/2.15.1:
  * Tested against Rails 3.2.21, 4.0.12 and 4.1.8 * Improved dependencies * Improved readme
Merge branch 'release/2.16.0'

* release/2.16.0:
  * Rails 4.2.0
  Rails 4.2.0
  Tested against rails 4.2.0.rc1
  tested against rails 4.2.0.beta4
  Rails 4.2.0.beta2 support
* Ruby 2.2 compatibility
Merge branch 'hotfix/2.16.1' into develop

* hotfix/2.16.1:
  * Ruby 2.2 compatibility