RubyMine error when trying to go to declaration

Clicking 'Apple' + 'Left Click' to go to a declaration doesn't work and consistently puts an error in

~/Library/Logs/RubyMine20/idea.log

The error is:

ERROR - by.ruby.lang.RubySupportLoader - org.jruby.exceptions.RaiseException: undefined method `inflections' for ActiveSupport::Inflector:Module

The stacktrace can be seen here:

https://gist.github.com/957356

I think the error started when I downgraded from RubyMine 3.1 to Rubymine 2.0.2.  I wonder if there is some leftover cruft from the RubyMine 3 uninstall.

Can someone help me find the file I need to delete from the Rubymine 3 uninstall, or where to put a file to help Rubymine find this inflector module