Make example 'entry_points' parameter a dictionary

Change-Id: Idad5a1b2d6aaee456cdc3a52554c1d7ddd51a696
Fix straggling uses of direct-to-database queries in nova-network

There were a few remaining calls directly to the database module
left in nova-network. These would fail because of the wedge we
put in place specifically to catch this case. However, we don't
test VlanManager in the gate, which means we didn't catch them
until now.

This required adding two more methods, one each to Network and
NetworkList, but they are both extremely simple.

Change-Id: Iecc382074f060da1bd6f740d7bde0b20a0be2fcf
Closes-bug: #1304724
Merge "Make example 'entry_points' parameter a dictionary"
Merge "Fix straggling uses of direct-to-database queries in nova-network"