Setup New Relic for app monitoring

Add 'newrelic_rpm' gem and config file.  The license key was removed
from the config/newrelic.yml file and must be provided via the
NEW_RELIC_LICENSE_KEY environment variable
Explicitly set license key from environment var

The docs say that any environment variable starting with `NEW_RELIC_`
will automatically be picked up by the agent, but it doesn't seem that
way - at least not with the license key.  So I had to manually specify
it in the newrelic.yml file as `ENV['NEW_RELIC_LICENSE_KEY']`.

Also set the app name :)
Merge pull request #9 from cit-jmu/newrelic

New Relic for app monitoring