Adds hypervisor statistics to admin dashboard

Uses the existing d3 visualizations along with the hypervisor
stats API in Nova to display some useful at-a-glance information
about the utilization of your cloud.

Implements blueprint hypervisor-info

Change-Id: If71c533529a1f51d565eafb0b9b84f6ce93427c8
Merge "Adds hypervisor statistics to admin dashboard"