[Buildbot] #3178: remove IStatusReceiver and friends and implementers

[Buildbot trac]

#3178: remove IStatusReceiver and friends and implementers
------------------------+-------------------
Reporter:  dustin       |      Owner:
    Type:  enhancement  |     Status:  new
Priority:  major        |  Milestone:  0.9.0
 Version:  master       |   Keywords:
------------------------+-------------------
 In master, there's no longer any such thing as a status receiver, so the
 continued presence of this interface is misleading.

--
Ticket URL: <http://trac.buildbot.net/ticket/3178>
Buildbot <http://buildbot.net/>
Buildbot: build/test automation