Check compatibility with more Rubies and Railses

* Ruby 2.1.1
* Rails 4.0.x
* Rails 4.1.x
* Rails 4.2.x
Get rid of Jeweler, edit gemspec directly
Trying to fix tests for Rails 4.x
rewrite gemspec
fix test helper
remove railties.engines entirely
rails 4.0 has HEAD as well
README update, gemspec update [ci skip]
rails 4 fix
rails 3 has railties.all
jsonp rails 2.3
bump to v0.3.0