Remove the Cisco Nexus monolithic plugin

The Cisco Nexus monolithic plugin does not work without the Open
vSwitch plugin. The Open vSwitch plugin is scheduled to be removed
as per #1323729. This patch removes the Nexus Hardware switch
related plugin code. The N1KV virtual switch related code will
still remain in the tree as it doesn't depend on Open vSwitch
plugin.

Closes-Bug: #1350387
Change-Id: I2542e92c25e9280e975c3903afb9114e850a966a
Merge "Remove the Cisco Nexus monolithic plugin"