Change the role order in os-network

The migerate network database in openstack-network::server depends on
the network plugin package should be installed first, so I move the
os-network-server to the end of run list.

Closes-Bug: #1270708

Change-Id: I0ebc0c7d30dc2132e36eda0ae613e4f92f24361b
Merge "Change the role order in os-network"