Extend volume for GlusterFS

Add support for extend volume.

Change-Id: Ie9ba67d91de2da43e6b857b4256a445c5269c5cd
Remove deprecated code from Nexenta Exception class

Change-Id: I4242fce8b3f10c863d38cd2f81c2aab9fea77e24
Merge "Extend volume for GlusterFS"
Merge "Remove deprecated code from Nexenta Exception class"