Do refactor for neutronv2 driver
Do refactor for neutronv2 driver

Aims to keep consistence of datasource driver state,
and avoid the conflict between datasource row list and
datasource updating state. Do some refactor for
neutronv2 driver, use a temporary state to collect row data,
then override the self.state table one by one.

This is a demo for getting some feedback from other reviewers.
If the way is approved, same refactor will been implemented on
all other datasource drivers by following the pattern.

Change-Id: I74102f35ca16b82419de145a5263eb5d135e82a3
Partial-Bug: #1473924

ramineni/my_congress,ramineni/my_congress,ekcs/congress,ekcs/congress,ekcs/congress,openstack/congress,ramineni/my_congress,ramineni/my_congress,ekcs/congress,openstack/congress