GlusterFS: passthrough devstack config
GlusterFS: passthrough devstack config

This patch provides the glusterfs devstack configuration through
DEVSTACK_LOCAL_CONFIG variable, rather than having devstack-gate
need to know about devstack glusterfs plugin.

Change-Id: I8150d54c1100814ca40e9f6471fd4e979d199967

coolsvap/project-config,citrix-openstack/project-config,anbangr/osci-project-config,dongwenjuan/project-config,openstack-infra/project-config,coolsvap/project-config,openstack-infra/project-config,dongwenjuan/project-config,anbangr/osci-project-config,open-switch/infra_project-config,Tesora/tesora-project-config,citrix-openstack/project-config,noorul/os-project-config,Tesora/tesora-project-config,open-switch/infra_project-config,noorul/os-project-config