Fix License vs. API Key Mix Up

Here's a preliminary patch for my License vs. API Key Mix Up

It now has the two key options

    api_key: %newrelic_api_key%           # New Relic API
    license_key: %newrelic_license_key% # New Relic License Key

license_key is new and is actually the license key, the api_key has the old behaviour restored and is for example used in the deployment notification script

I will do some more tests later to see if this really works now as expected

If you already have some feedback, do not hesitate ;)

Sorry for the "fuck up"