tools/mount_gcsfuse: Don't pass through auto, noauto, or nouser.
tools/mount_gcsfuse: Don't pass through auto, noauto, or nouser.

This is in addition to user, which we were already suppressing. We don't
care to see these options, and fusermount chokes on them.

For #118.

GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,GoogleCloudPlatform/gcsfuse,kahing/gcsfuse