[Buildbot] #2818: [nine] rewrite buildsteps to not write to status

[Buildbot trac]

#2818: [nine] rewrite buildsteps to not write to status
------------------------+--------------------
Reporter:  dustin       |      Owner:  dustin
    Type:  enhancement  |     Status:  new
Priority:  major        |  Milestone:  0.9.0
 Version:  0.8.7p1      |   Keywords:
------------------------+--------------------
 Part of #2646.

 Buildsteps currently write to both status pickles and the data API.  They
 should only write to the data API.

--
Ticket URL: <http://trac.buildbot.net/ticket/2818>
Buildbot <http://buildbot.net/>
Buildbot: build/test automation