Move old gemfiles to separate folder.

So we can still to this version in travis.
Make tests rails 4 compatible.
Make sure travis builds the tested version.
Make sure travis builds rails 3 and rails 4 version.
No longer build against ree, use jruby instead.
Fix the name of the rails-3.1 gemfile.
Add extra tests.

To make sure #145 is not an error.
Use rbx in 1.9 mode.
Use the better nomen double instead of stub.
Make sure travis build will work correctly.

- provided a correct gemfile (and upgraded to rails 3.2.13)
- removed jruby again (sqlite3 is still a problem?)
Version bump to 1.2.0
Adapted README to show we are now compatible with rails 4.