Update release notes
Sort/group feature release notes

For example, all the Git source step notes are together.
Fix formatting of :bb: macros in relnotes
:bb: -> :bb:bug:
Add missing bb:step and bb:sched
More release note formatting
Fix use of :py:mod:
Move slave-side steps note to deprecations.
Update relnotes with explicit versions
archive release notes
Don't send branch as ref/heads/master
Add relnote for #1069
Fix GitPoller setting invalid branch (PR #1069)
Merge branch 'buildbot-0.8.9'
Skip flaky tests, with logging

This fixes #2748 (and opens a bunch of other bugs!)
don't try to fix PB on old Twisted versions
Can't use inline conditionals on Python-2.4
replace with statements with explicit patching
work around missing os.errno on py24
replicate any() for python-2.4