add "--no-user" option to avoid referencing the "my-cmssw" repository

add "--no-user" option to git-cms-init, git-cms-addpkg and git-cms-merge-topic to avoid referencing the "my-cmssw" repository.

git-cms-addpkg and git-cms-merge-topic simply pass the option (along with --ssh and --https) to git-cms-init.