Upgrade to Rails 3.0.18

Security fixes. https://www.pivotaltracker.com/story/show/35132281
Upgrade to Rails 3.0.19 to address security issues
Installed New Relic gem.

Also installed the default configuration, because (a) it's changed, and
(b) the old one was specific to staging, where this one gets
configuration from the Heroku environment.

https://www.pivotaltracker.com/story/show/41055879
Merge: New Relic, security updates.