Fixes LP853979
Remove the FK references for network data.
Remove unused db functions that used the FK's
Update db functions to not joinload
Update notification to optionally take network_info if compute has it
Update EC2 Api to use the network cache, falling back to rpc.call
Remove test_instance_get_project_vpn_joins which tests calls not used
Change-Id: I1a01ccc5ebcf7efeafe014af62be893325bb0825
0c90acfb15