Remove pause/unpause NotImplementedError API layer

There are 2 kinds of RPC call from API layer to compute layer,
one is cast and another is call. For cast, the RPC message will
be posted and the API service will not wait for the message to
be processed. So it won't be able to catch the exception raised
in compute layer, so catch and handle the exception is useless
and error leading. This patch removes code in API layer for
pause and unpause functions.

Change-Id: I7cbb8179b3eec8496b90ff5cf07397522d52c5de
Downgrade the warn log in network to debug

Downgrade the log from warn to debug for overquota.
Didn't remove it because it's called internally and it might
be helpful for operater to take a look.

Change-Id: I1d3c27a8d97085d9919180a28018b234392f28e4
Convert network/api.py fixedip calls to use FixedIP object

This makes the network/api.py module use the FixedIP object for
fetching fixedip information instead of direct database access.
There was not complete test coverage for these calls, so it is added
here.

Note that this includes a change to the FixedIP object, which allows
for the case that fixed_ip_get_by_floating_address() can return
None. This is technically an RPC-visible change that would normally
require a version bump. However, I don't think it's worth bumping
the version here since this bug would cause calls to explode in a
non-useful way, thus preventing callers from being able to tolerate
the case where the DB call returns None.

Change-Id: Id8a9c8d2d10ddfaf0990258ac496da7c48a9b28c
Add policy on how patches and reviews go hand in hand

There is currently a misconception about how a patch gets merged:
Author proposes a patch, review team reviews it. Us, and Them. Instead
it should be a 'We.'
If the review bandwidth doesn't grow at the same rate as the patch
proposal rate then we end up with a massive backlog where people are
pinging cores for reviews.

Record a recommended policy of asking patch authors to offset the review
resources spent on their patch by reviewing other patches.

Change-Id: I50653f8ea58240fa664519f544ce16b2adf39006
Update devref out-of-tree policy grammar error

The sentence structure was wrong and therefore bugging me.

Change-Id: Iac7f0803d9cc9b73075f3f0aa23e690386be71ee
Make spawn_n() stub properly ignore errors in the child thread work

When we call spawn_n() normally, we fork off a thread that can run or
die on its own, without affecting the parent. In unit tests, we stub
this out to be a synchronous call, but we allow any exceptions that
occur in that work to bubble up to the caller. This is not normal
behavior and thus we should discard any such exceptions in order to
mimic actual behavior of a child thread.

Change-Id: I35ab21e9525aa76cced797436daa0b99a4fa99f2
Related-bug: #1349147
Merge "Downgrade the warn log in network to debug"
Merge "Remove pause/unpause NotImplementedError API layer"
Merge "Update devref out-of-tree policy grammar error"
Merge "Make spawn_n() stub properly ignore errors in the child thread work"
Merge "Add policy on how patches and reviews go hand in hand"
Merge "Convert network/api.py fixedip calls to use FixedIP object"