Replace deprecated import of ABCs from collections
Replace deprecated import of ABCs from collections

ABCs in collections should be imported from collections.abc and direct
import from collections is deprecated since Python 3.3.

Change-Id: I6a96d3ed3f046f87822c4cedaa51041885a2d3b6

openstack/cloudkitty-dashboard,openstack/cloudkitty-dashboard,stackforge/cloudkitty-dashboard,stackforge/cloudkitty-dashboard,stackforge/cloudkitty-dashboard,openstack/cloudkitty-dashboard