Upgrade to an RC version of Rails 4.1 -- livin' on the EDGE.

 * Run the rails:update rake task.
 * Manually install tzinfo-data gem as a missing dependency for rails.
   This should only be a temporary workaround and should be fixed by the
   time 4.1 final comes out.
Install MailCatcher so we can use ActionMailer without an actual mail server.
Add mailcatcher settings to Rails development environment settings.