Finish ruby2.0 compatiblity in testing setup.

* Split out gemfiles in travis for explicit matrix.
* Update gemfiles for ruby2.0 compatibility
** rails/rails#9406 <- makes rails 3.2 Ruby 2.0 compatible, meaning the first version we'll test with and support is this
** Use older version of rubygems for rails 2 compatibility
* Update dummy rails3 test app and rails loading tests.