Fix Meteor integration and make more robust

Fix issues encountered in PR #2059.

Now you only need to set the package name once in the first line of `package.js` and the scripts will take care of the rest, including passing `--create` if the package is published for the first time.

Meteor/Atmosphere repos can't really be renamed at the moment... And unfortunately [someone](http://stackoverflow.com/questions/27096726/how-can-i-find-out-who-owns-a-meteor-developer-account) took the `moment` namespace. I've asked how to figure out who they are. Hopefully they'll transfer `moment` to you, and then you can [create an organization](https://meteor.hackpad.com/Meteor-developer-accounts-organizations-bqdepZkDB3w) so different devs can push to `moment:moment`.

But for now, `ichernev:moment` would be great, as it will show official Meteor integration from Moment.js.