gluster: verbs for managing services

Verbs to manage or get status of gluster/system services.

glusterServicesGet: To get the status of given system services
Output structure:
{'services': [{'name': SERVICE_NAME,
               'status': STATUS,
               'message': MESSAGE},..]}

glusterServicesAction: To start/stop/restart system services like
glusterd, memcached, gluster-swift-account, smb, gluster-swift-container..
Output structure:
{'services': [{'name': SERVICE_NAME,
               'status': STATUS,
               'message': MESSAGE},..]}

Change-Id: I8a16bf566d17e186a66503391dfd04b2f2bb4bb4
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Signed-off-by: Timothy Asir <tjeyasin@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/11094
Reviewed-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>
Reviewed-by: Adam Litke <agl@us.ibm.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>