Private github repo auth support is the main target

• What does github allow/use?
• For others, ssh is most likely used - investigate options from git
• gits default is to use ssh, you can specify a user
• There are a number of options for passing a credentials listed in http://www.kernel.org/pub/software/scm/git/docs/git-config.html

Changed the scope of this task to cover backend authentication on unix. Tests will be separate sub-tasks.