Change chown_restricted for GPFS FSAL to FALSE.

GPFS allows users to take ownership of file if the ACL allows CHOWN for
that user.

Signed-off-by: Srikrishan Malik <srimalik@in.ibm.com>
Accept numeric IDs for users and groups.

If the user/group name  contains only digits, with no leading zeros
and does not contain '@', it will be treated as user/group with
UID/GID same as the corresponding integer value of the name.

Signed-off-by: Srikrishan Malik <srimalik@in.ibm.com>