Cleanup messageFormatter example to use logs from build steps instead of directly using build logs
Remove assert from subscribeConsumer

This method is used by the WebStatus, and thus necessary (even for
new-style steps) in eight.
Merge pull request #1246 from anish/eight-msgfmt

Cleanup messageFormatter example to use logs from build steps instead of directly using build logs
Merge pull request #1249 from djmitche/subscribeConsumer-assert

Remove assert from subscribeConsumer
Merge pull request #1244 from wmswms/eight

Guard against content spoofing.

Fixes ticket:2589
apply one-sentence-per-line rule to the changed section
update documentation for GitHub change hook

* misc syntax, wording and cosmetic changes
* move mention of standalone server to the beginning of the section
* fix link to the GitHub tutorial for adding webhooks
* make list of parameters of GitHub webhook and their correpsonding
  values explicit

Fixes ticket:2938
Merge sa2ajj/buildbot:bugfix-2938 (PR #1253)