Support Rails 4
Only support Rails 4 for ruby version 1.9.3 and above
Add more badges to README.md
Correct gemspec
Fix status badge
Don't test rails 3.1.0
Drop support for ruby 1.8.7
Update README.md [ci skip]
Update README.md [ci skip]
Merge pull request #2 from jhnvz/enhancement/support-rails4

Support Rails 4