Changed "homepage" to point to module repo

Moved "nodesecurity.io" into author URL, changed homepage to be the GitHub repo since it gives install and usage information (and nodesecurity.io doesn't give any Grunt package info).

No real reason apart from it was making @GruntWeekly auto-Twitter bot act weird and sending you to a page w/ no context on the module.
Feel free to give a deep laugh and send this to the trash bin.