Migrate network database

Migrate network database like other cookbooks do (openstack-identity,
openstack-nova,openstack-image etc.). The database migration will
make the OpenStack upgrade using the cookbooks easier.

The patch passes the template_file from common.rb to server.rb using
node['openstack']['network']['plugin_config_file'].

Change-Id: Ic98d2908876e45b870e32dfb37cfcd649962e2e6