features/glupy: Rename Glupy module to avoid namespace conflict

* Rename gluster.py to glupy.py to avoid namespace conflict (#1018619)
* Move the main Glupy files into glusterfs-extra-xlators rpm
* Move the Glupy Translator examples into glusterfs-devel rpm
* Add Glupy entry to the MAINTAINERS file

BUG: 1018619
Change-Id: I48de598ba5ae8eec0e7e276bbcca1abb0e549cef
Signed-off-by: Justin Clift <jclift@redhat.com>