sqlalchemy version changes

Don't fail on sqlalchemy versions with characters in them With that fix,
0.8.0 seems incompatible with sqlalchemy-migrate 0.7.2, which is the
latest version, so mark it as incompatible for now.
Fix detection of windows path module from slave.
Fix detection of vcs state dir on windows.

`/` should work as a path separator on windows, but we do have the
means to use the correct platform specific path manipulation functions,
so use them.
Merge branch 'svn-paths' into buildbot-0.8.7
Fix revlink documentation.

The documentation incorrectly used basic rather than python regexes.
Merge branch 'revlink-docs' into buildbot-0.8.7
Report missing python-dateutil at config time, rather than later.
Merge pull request #588 from tomprince/dateutil-error

Report missing python-dateutil at config time, rather than later.
remove log.msg invocation that can unintentionally include unicode; fixes #2407.
doc: BuildFactory has .addStep, not .append.
Merge commit '021fdeadc1473ae75c18f8801afe76918a3159b0' into buildbot-0.8.7
Raise ImportError instead of exiting, if buildbot.test can't be imported.

This apparently causes issue with 'pydoc -k', and is in general not nice.
Trial still fails with a sensible error message.

This is a slave-side reflection of commit 126e02341c76bd5a027c2ca5a8467aa5708228f2
Fake merge branch 'buildbot-0.8.7'

The code was merged, but not recorded in
daa659cb4e0c83c94fb90445bf179e74126c3f2d.
Replace non-inlineCallbacks uses of DeferredLock.acquire.

Refs #2409.
call item.asDict, if the method exists, in status_push.  Fixes #2415.
Fix perforce patch generation
handle errors showing tracebacks better
Merge branch 'myfixes' of git://github.com/mx-mad/buildbot
Merge branch 'failure-showing-failure' of git://github.com/djmitche/buildbot
don't run sqlalchemy betas, either