Fixes #7013 - pin apipie-rails to < 0.2.3

0.2.3 was released with a Ruby 1.8.7 incompatible syntax method
definition. [This](http://ci.theforeman.org/view/Core/job/test_develop/795/database=postgresql,ruby=1.8.7/console) has been breaking test_develop in Jenkins for a day.

The fix on apipie-rails should be trivial, I'm working on it.