metadata: change 'source' to point to git repo

The docs say 'source' is "The source repository for your module." Using puppetlabs-apache
as an example the source repo has been updated to point to the git repository rather than
the GitHub webpage.

metadata.json

@@ -4,7 +4,7 @@
   "author": "James Fryman",
   "summary": "Puppet NGINX management module",
   "license": "Apache License Version 2.0",
-  "source": "http://github.com/jfryman/puppet-nginx",
+  "source": "https://github.com/jfryman/puppet-nginx.git",
   "project_page": "http://github.com/jfryman/puppet-nginx",
   "issues_url": "https://github.com/jfryman/puppet-nginx/issues",
   "description": "This module can be used for basic NGINX Management",