Add new meters for swift

    This patch adds new meters:
        -storage.containers.objects
        -storage.containers.objects.size.
    These meters are implemented through a polling Swift

blueprint: https://wiki.openstack.org/wiki/Ceilometer/blueprints/pollster-swift

Change-Id: Ic1f3aaf351db0b99392eb13d4f31f2732f87f816
Merge "Add new meters for swift"