Update needed for New Relic Recipe (support EU)

[ferremek]

Hey guys,

Just want to give a headsup that https://github.com/deployphp/deployer/blob/master/contrib/newrelic.php needs to be updated. The case is that the New Relic URL is different for EU customers.

• Current: https://api.newrelic.com/v2/applications/$appId/deployments.json
• EU Customers: https://api.eu.newrelic.com/v2/applications/$appId/deployments.json

So there probably needs to be a setting added where users can set that they are a New Relic customer from the EU.

Besides this, thanks for all the hard with Deployer! It's awesome!