Refactor kwapi unit test

ceilometer/tests/energy/test_kwapi.py has very similar test cases,
this patch refactors those unit test code.

Change-Id: Iaedee8d6be6b58147413295b39d8d8b152caa39a
Drop anyjson

oslo.serialization is a drop in replacement and already being used

Change-Id: I479221a9d4ec34cfef951d127af249e8c9432c29
Merge Central and Compute agents to *polling agent*

Implements-Blueprint: merge-compute-central-agents

Change-Id: I0e8c38ba624d0f9c88582a8b2d7180e808d262a7
Fix docs to suit merged compute/central agents concept

DocImpact: Fix agents-related docs to describe polling agent
Related-Blueprint: merge-compute-central-agents

Change-Id: If377ac49bf75c0698f4af6be021e8354240f4e42
Merge "Merge Central and Compute agents to *polling agent*"
Merge "Fix docs to suit merged compute/central agents concept"
Merge "Drop anyjson"
Merge "Refactor kwapi unit test"
implement notification coordination

this patch enables coordination of notification agents by splitting
pipelines across agents. a single-worker agent is provided that
skips the overhead of IPC. a multi-worker agent is added that uses
internal queue to redirect samples to correct pipeline.

Implements: blueprint notification-coordination
Change-Id: If8503ee70217025106a188f40a6e4ea8c49a89f4
ensure unique pipeline names

for notification agent coordination, we requeue items based on the
pipeline name. to ensure we have correct queues for pipeline, we
should make sure pipeline names are unique.

Change-Id: I1b3e7cf1206fd11ab7fde15233cdd19416322acc
Implements: blueprint notification-coordination