engine : Refactored gluster volume profile query

This patch refactors the volume profile query
to take an additional boolean parameter nfs which
helps to query the vds for 2 types of stats
nfs and brick profile stats

Change-Id: I41d80dbb8b6865f67fcadf78baed2a813c423d03
Signed-off-by: Anmol Babu <anbabu@redhat.com>
Signed-off-by: Sahina Bose <sabose@redhat.com>
Signed-off-by: Anmol Babu <anbabu@redhat.com>