Fix cleaning of rack-test-rest paths when bundler adds version.

When bundler installs this locally it will tack on the version number to the directory path, thereby breaking this match.

Example path: `/some/dir/.bundle/gems/ruby/1.9.1/gems/rack-test-rest-0.5.0/lib/rack-test-rest.rb`

This should match the conditional version string. /cc @nextmat