Update gpfs driver volume creation process

Modify gpfs driver to set file permissions in
a more consistent way.

Modify image_utils.resize_image to allow caller
to request it be run as root.

SecurityImpact
Change-Id: Ic01d91c0d660c74095e8d2b212279b39b9b9dc05
Partial-Bug: #1260679
Merge "Update gpfs driver volume creation process"