HP lefthand driver filter and evalautor function

HP lefthand driver filter and evalautor function

This patch implements the merged change in the scheduler
https://review.openstack.org/#/c/129987/ in HP lefthand driver.

1. Added filter_function and goodness_function strings

2. Added 2 stats total_volumes and capacity_utilization so they can be
used as the part of the formula in filter_function or goodness_function
string.

implements: blueprint hplefthand-driver-supplies-filtering-weighing-functions
Change-Id: I6193196ba1930f9d07865c062f12573e1570f290