Support listening on multiple queues and routes on the same pulse connection

[marco-c]

I'll rebase once #18 lands.

[La0]

I pushed a modification to your PR to add the routing information in the message sent to clients.
The events pulse clients would receive a payload enabling them to triage the payloads using exhange & routes. I also found the other routes (which are the ones we are mostly intrested in for triage)

{'body': {'runId': 0,
          'status': {'deadline': '2019-11-27T05:36:19.459Z',
                     'expires': '2020-11-25T05:36:19.459Z',
                     'provisionerId': 'gecko-t',
                     'retriesLeft': 5,
                     'runs': [{'reasonCreated': 'scheduled',
                               'reasonResolved': 'completed',
                               'resolved': '2019-11-26T08:28:21.535Z',
                               'runId': 0,
                               'scheduled': '2019-11-26T07:51:33.267Z',
                               'started': '2019-11-26T08:04:56.852Z',
                               'state': 'completed',
                               'takenUntil': '2019-11-26T08:41:57.869Z',
                               'workerGroup': 'aws',
                               'workerId': 'i-03e2be4d85264417e'}],
                     'schedulerId': 'gecko-level-3',
                     'state': 'completed',
                     'taskGroupId': 'acRnT7fsQvaibi0I3-cLZA',
                     'taskId': 'CJyfokx5Sjaw39liC1skDw',
                     'workerType': 't-win7-32-gpu'},
          'task': {'tags': {'createdForUser': 'gwatson@mozilla.com',
                            'kind': 'test',
                            'label': 'test-windows7-32-shippable/opt-reftest-no-accel-e10s-4',
                            'os': 'windows',
                            'retrigger': 'true',
                            'test-type': 'reftest',
                            'worker-implementation': 'generic-worker'}},
          'version': 1,
          'workerGroup': 'aws',
          'workerId': 'i-03e2be4d85264417e'},
 'routing': {'exchange': 'exchange/taskcluster-queue/v1/task-completed',
             'key': 'primary.CJyfokx5Sjaw39liC1skDw.0.aws.i-03e2be4d85264417e.gecko-t.t-win7-32-gpu.gecko-level-3.acRnT7fsQvaibi0I3-cLZA._',
             'other_routes': [b'route.tc-treeherder.v2.autoland.40fc032b53b7'
                              b'e6bbe186425f89defbead3491b7e.101555',
                              b'route.coalesce.v1.autoland.1b40bdf4a8bf581fe'
                              b'30f']}}

[marco-c]

The commit you added looks good to me!

[La0]

Let's merge this awesome piece of collaborative work.