Don't allow gitfs to be run as `root`
Don't allow gitfs to be run as `root`

This restriction will save us from plugging several security holes in
the long run.

Signed-off-by: Ramkumar Ramachandra <5c355d1d38066ed0c5de420d67c1b5ed0687c4bd@gmail.com>

artagnon/phoenixfs,artagnon/phoenixfs,artagnon/phoenixfs