Clean imports in code
Clean imports in code

In some part in the code we import objects.
In the Openstack style guidelines they recommend
to import only modules.

Change-Id: If5170c8383b0a85a18793d6ed85c91f2150ba81a
Partial-Bug: #1543101

openstack/neutron,igor-toga/local-snat,noironetworks/neutron,openstack/neutron,mahak/neutron,eayunstack/neutron,sebrandon1/neutron,bigswitch/neutron,huntxu/neutron,cloudbase/neutron,sebrandon1/neutron,wolverineav/neutron,MaximNevrov/neutron,klmitch/neutron,mahak/neutron,openstack/neutron,noironetworks/neutron,eayunstack/neutron,mahak/neutron,cloudbase/neutron,klmitch/neutron,huntxu/neutron,MaximNevrov/neutron,bigswitch/neutron,wolverineav/neutron,igor-toga/local-snat