Change status of floatingip upon association and disassociation

Currently, in networking-plumgrid when a floatingip is associated to a VM its status is ACTIVE and when it is disassociated from a VM the status is still ACTIVE, which results in discrepancy between the stock OpenStack behaviour and networking-plumgrid, it also results in failure of a tempest scenario test case:

tempest.scenario.test_network_basic_ops.TestNetworkBasicOps.test_network_basic_ops
Traceback (most recent call last):
  File "/opt/stack/tempest/tempest/test.py", line 126, in wrapper
    return f(self, *func_args, **func_kwargs)
  File "/opt/stack/tempest/tempest/scenario/test_network_basic_ops.py", line 400, in test_network_basic_ops
    msg="after disassociate "
  File "/opt/stack/tempest/tempest/scenario/test_network_basic_ops.py", line 203, in check_public_network_connectivity
    self.check_floating_ip_status(floating_ip, floatingip_status)
  File "/opt/stack/tempest/tempest/scenario/manager.py", line 734, in check_floating_ip_status
    st=status))
  File "/usr/local/lib/python2.7/dist-packages/testtools/testcase.py", line 350, in assertEqual
    self.assertThat(observed, matcher, message)
  File "/usr/local/lib/python2.7/dist-packages/testtools/testcase.py", line 435, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: 'DOWN' != u'ACTIVE': FloatingIP: <"FloatingIP" addr="192.168.223.55" id="eff528e0-0c52-4d2e-857a-d113137a7f69"> is at status: ACTIVE. failed to reach status: DOWN

We need to introduce a way to track the status of floatingip upon association and disassociation.