Correct default usage filtering on overview page

On the overview page, the usage data showed by default was not filtered by
the dates shown on the date selectors. This can lead the user to wrong
conclusions about resource usage.

This patch corrects the default filtering dates to match the dates showed
by default on overview (first day in the month to current date).

Change-Id: I37a240d784ca0826821c125f06922d2c1d1e8659
Closes-Bug: #1294668
Updated from global requirements

Change-Id: If0c07ca1d45da95ffe962f89d701d1bb09bcbbc1
Merge "Correct default usage filtering on overview page"
Merge "Updated from global requirements"
Merge branch 'master' of git://git.openstack.org/openstack/horizon into poc