Merge 7337861 "Adding GPFS Manila driver"

Conflicts:
	etc/manila/rootwrap.d/share.filters

Change-Id: I8840e3ff29adb545aab17084f82ec0d618a6d565
gpfs: use ganesha.utils provided execution routines

This patch is not necessary, it's purpose is just to
cut back on redundancy. No change in functionality.

Change-Id: Ic921fb534b3eca43fec05bc272c7464c6a38b1db
gpfs: retire remove_export auxiliary method

Manila provides its intended purpose at framework
level, cf.

https://github.com/stackforge/manila/blob/2014.2.b3/manila/share/manager.py#L265

Change-Id: I1ab3c8bae8941e9a5fb4fc547d7e93c876c4680d
gpfs: implement Ganesha backend with manila.share.drivers.ganesha

This is an interim commit, which just introduces the new,
manila.share.drivers.ganesha based helper class and
implements helper dispatch. This code is not functional, as
the helper interface used by the original code is not compatible
with the manila.share.drivers.ganesha.NASHelperBase helper
interface, on which the new class is based.

A subsequent commit will address interface incompability.

Change-Id: I4f7ed670eefef22967cd0c2aff711a0f06c51837
gpfs: compliance with manila.share.drivers.ganesha.NASHelperBase

The
  manila.share.drivers.ibm.gpfs.GPFSShareDriver
and
  manila.share.drivers.ibm.gpfs.KNFSHelper
classes are adjusted to use the
  manila.share.drivers.ganesha.NASHelperBase
interface as, respectively, consumer and provider.

Change-Id: I450a20676f2e067bfdc528bacde362ad71b61d43