Check for VPN Objects when deleting interfaces

When we delete Router interfaces/gateway,
we need to check if any VPN services are
associated with that router.

Closes-Bug:1261598

Change-Id: I7df2b8b130b47ec070d0b0a36b1a62df40532760
mock.assert_called_once() is not a valid method

mock.assert_called_once() is a no-op that tests nothing. Instead
mock.assert_called_once_with() should be used (or use
assertEqual(1, mock_obj.call_count) if you don't want to check
parameters).

Borrowed HACKING rule from Davanum Srinivas's nova patch to
prevent it from appearing again.

Change-Id: Idac1d3c89c07e13c9a209663f4e557fcb7547821
Closes-Bug: #1365751
Closes-Bug: #1300265
Modify docstring on send_delete_port_request in N1kv plugin

N1kv plugin: Modify docstring on _send_delete_port_request method

Change-Id: I64d34878ffd8f6db703e4c1d9849032fef9bae96
Closes-Bug: #1381277
Merge "mock.assert_called_once() is not a valid method"
Merge "Modify docstring on send_delete_port_request in N1kv plugin"
Merge "Check for VPN Objects when deleting interfaces"