changing gluster dir to glusterfs

making this change to avoid package conflicts with
gluster-swift and glusterfs-api rpm. Eventually we will remove
the python code from glusterfs-api rpm and create a new rpm package
from libgfapi-python.

Change-Id: I1b20cd747e500aed17fba89f96e62423325b5230
Signed-off-by: Thiago da Silva <thiago@redhat.com>