vdsm-tool: add service management utilities

Change-Id: Idd1cbcf5fd00bb1ec73c5970be012e294b3b4c55
Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>
Reviewed-on: http://gerrit.ovirt.org/13701
Reviewed-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>
Reviewed-by: Ewoud Kohl van Wijngaarden <ewoud@kohlvanwijngaarden.nl>
Reviewed-by: Vered Volansky <vvolansk@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>