LU-6175 ha: add health_check routine to the MDS, MGS and OSD

Patch adds obd_health_check() methods in MDS and MGS to check
ptlrpc services health like OST does. Patch adds also health_check()
routine directly to OSD to check it is mounted and is not read-only.

Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: Ib4af652b08e7e3616ebb3b99ce3e4ad03bdd5ab5
Reviewed-on: http://review.whamcloud.com/13558
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>