Move agent cleanup scripts to cmd module
Move agent cleanup scripts to cmd module

Ensure naming consistency across the various entry points.

This patch better separates active elements of Neutron agents from
operator's utilities.

Along with [1,2,3], this is done to better delineate what the agent
module inner boundaries are about. More to follow to finish off the
cleanup.

[1] https://review.openstack.org/#/c/146024/
[2] https://review.openstack.org/#/c/145979/
[3] https://review.openstack.org/#/c/146239/

Change-Id: I1d2d2938aa7fa1c60e0f0dc70997778a1930efef

stackforge/networking-bigswitch,wolverineav/networking-bigswitch,openstack/networking-bigswitch,openstack/networking-bigswitch,stackforge/networking-bigswitch,wolverineav/networking-bigswitch