Turn on new relic agent logging.
Move settings from general.constants -> slingsby.settings
Add up-to-date instructions for running devserver to readme.

Also added instructions for how to authenticate towards facebook
in the devserver, and added a file 'secret_settings.py' to gitignore
(where you can store auth keys needed for the facebook auth).

Also corrected a typo in base.html.
Make the grunt provision and deploy tasks clean up after themselves.