GC deferred threshold for tests

This tweak allows us to save some time when running the test suite.
https://37signals.com/svn/posts/2742-the-road-to-faster-tests#all_comments
explains it better.

It went from 11m. 12s, to 8m, 50s, averaging two test runs.

Functional tests adapted to new permission model

Added oj to Gemfile to fix multi_json problem

fix for https://github.com/intridea/multi_json/issues/86 , which raised
when running some tests
Merge pull request #5 from eLobato/permissions_ares_change

Fixes mainly for functional tests