Fix check for mount.nfs helper installation

This fixes the issue for checking the
existence of mount.nfs helper program
in installation directories during
driver set up.

Closes-Bug:#1212286

Change-Id: If2fa925614bd42295eae0f62ba948e14a89e1343
(cherry picked from commit efd82e0265efbbfa43ff7ebb7523790b81299882)
Fix chown fail for nfs file without necessary permission

chown failed in case of volumes on nfs export when the
permission is not granted on the storage system. Upload
volume only requires read access on the nfs file and hence
chown is not neccessary when current user has read permission.
Chown only executed when read is not granted to the user.

Conflicts:

	cinder/image/image_utils.py

Change-Id: Ifa8eff7e79c6e4f15a1feb7cabec8cae8a0b0a83
Closes-Bug:#1221205
(cherry picked from commit 1498958299ccb807f406e9d257848cb4259e49e4)
Merge "Fix check for mount.nfs helper installation" into stable/grizzly
Merge "Fix chown fail for nfs file without necessary permission" into stable/grizzly