pass silent flag into addRemoteGit to error silently

With the change to maybeGithub where it now tries both the
	public and private git uris we should allow
	addRemoteGit to not print errors to stdout since that
	function is now recoverable by means of retry.

We only call addRemoteGit with silent set to true the first time
	and call it with silent set to false the second time
	so that when the cloning process fails the second time
	it will print to stdout/stderr