Neutron Support for Trove

trove needs to be adjusted to support neutron.

changes include (to be continued):

1. passing 'nic' during instance provisioning
2. associate/deassociate extra networks for existing guestagent vm
3. security group support
4. floating ip support

Currently only nova-network is supported; but as we know, nova-network might be soon deprecated, so we will need neutron support for these operations.

1. has been implemented.
This blueprint is to track work items for 2, 3, and 4.