Set up clone ICETests dev menu action.
This commit fixes a bug where the cloned repo wasn't added to the git repositories view. Also, it adds code to check for the user credentials on a git repo if need be. Added an extension point that let's users clone the ICETests repo from github. To acheive this, I added the ability to provide custom parameters to a given command. The ICETests extension point uses this to specify the clone directory as @user.home. Signed-off-by: amccaskey <email@example.com>