Add metering panel to admin console

Now it has usage tables for disk usage,
network traffic usage, network(neutron) usage,
objectstore usage, all agregates of project.

A multiseries linechart with choosable meters, group by, value and time
span.

Reasonable amount of tests implemented over all resource usage tabs.

Change-Id: I21342d595ee08da45707e909f3d9802707d912cc
Implements: blueprint admin-resource-usage-page