Correct network_model tests and __eq__ operator

The current network_model tests mix IP() with FixedIP()
in several places. This patch corrects this issue. This was discovered
while adding logic to determine if the network_cache needs to be updated.
While updating the __eq__ operator to check all of the objects fields
rather than just id there tests started failing.

Closes-bug: # 1260891
Related to blueprint: smarter-network-cache-update

Change-Id: I6d144aecf95725146aa0fc4f4fe5a3f16c434d14
Merge "Correct network_model tests and __eq__ operator"