A testing Gemfile with ActiveRecord locked to 3.2

Can be used as: BUNDLE_GEMFILE=./Gemfile-ar32 bundle exec rake test
Use Thread.new vs CloudCrowd.defer in node

Worker nodes do not require DB access.  Since the defer call wraps a connection pool it's usage was causing excessive
connections and was causing errors if the node's configuration didn't have a database setup.

Reported in issue #44
Wait for thread to fire callback on test.

This was intermittently failing because the thread might not have fired the callback stub by the time we tested.
Use ActiveRecord 3.x compatible syntax

find_or_create_by was introduced in version 4.  Reported in #44