Use SSH to push to public Github repositories

[cjcjameson]

Addresses #130

http://engineering.pivotal.io/post/git-push-instead-of/

[d]

shouldn't this be a local per-repository setting of remote.origin.pushurl?

[cjcjameson]

It's recommended as a global setting because it's more convenient than setting a push URL for each (possibly forgetting).

[joemoore]

We are declaring PR bankruptcy as per #295.

Please review recent changes and direction and resubmit if needed.

Thank you!