Upgrade Mockr to Rails 3.0.20

To mitigate CVE 2013 0333:

https://groups.google.com/forum/?fromgroups=#!topic/rubyonrails-security/1h2DR63ViGo

Related Story:
  http://www.pivotaltracker.com/story/show/43496809 (delivered)
  ("Patch Mockr for Rails CVE 2013 03333")

Change-Id: If24695ba3753e0864e1e95c631d1f4a8d0cb0da2
Reviewed-on: https://gerrit.causes.com/17947
Tested-by: Aiden Scandella <aiden@causes.com>
Reviewed-by: Lann Martin <lann@causes.com>