png status by revision hash
fix pngstatus test
update docs for statuspng
Merge kviktor/buildbot:png-status-by-revision (PR #1083)
Revert "sphinx doesn't seem to support relative paths for logos anymore"

This reverts commit a655a504309db8584ae582065fe27548a16c3dd3.
Merge branch 'master' into nine

Conflicts:
	master/buildbot/status/web/pngstatus.py
	master/buildbot/test/unit/test_status_web_statuspng.py
	master/docs/manual/cfg-statustargets.rst