Update 3PAR driver

Update 3PAR driver

Added support for get_volume_stats()
Add sanity checks for:
    Ensure the CPG lives in the Domain that's configured.
    On 3PAR systems, the create volume from snapshot has to be
    the same size. The driver now checks to make sure that they
    are the same size.
    Now using volume and snapshot id's instead of the names.
    Checking for optional fields before using them(i.e. description).
    Added a new method get_ports() to gather the active array ports.
    Fixed inline comments, added a space between the comment and # sign

Change-Id: Ie2aed38c6349bb5ee8bbea4d0928cd606427a26f