Username/Password Prompt for Clone, Push, Pull

This contains a username/password prompt dialog for clone, push, pull when a username and password are not included in the remote git url.

You can leave the remote url either with a username or with none at all (https://user@github.com or https://github.com). 

Screenshot
http://imgur.com/ZGTYpRZ
Argh, mixed whitespace attack :P