Added changes to make the gem Rails 4 compatible

1) Updated gemspec to allow Rails 4.x
2) Made changes to specs and Rakefile to allow them to run under Rails 4
3) Modified specs to eliminate a number of deprecation warnings
4) Updated the Gemfile and database.yml so that the specs run against multiple Rails versions, JRuby
5) Added a .travis.yml
6) Added another AR class in specs to allow the specs to run against Rails 3.1.x
Merge pull request #31 from petergoldstein/feature/rails_4_support

Added changes to make the gem Rails 4 compatible
Rails 4 compat with scopes /credit @mchapman17
Add more info to dupe value error
Add commented require for simple_form in generator
Merge remote-tracking branch 'upstream/master'

Conflicts:
	spec/spec_helper.rb