Pin distribute to 0.6.34.

For some reason the buildout that we create in the test run gets
updated to a newer version of distribute, but not the newest.  So we
pin that version here, otherwise the first doctest goes wrong
because you get a few extra lines at the start, about upgrading and
restarting the buildout.
Make the blobstorage dir only readable for the current user.

Otherwise you get a ZODB warning on startup.  This uses code from the
ZODB, which does the same when Zope starts up and the blobstorage
directory does not exist yet.
Merge branch 'master' of git://github.com/plone/plone.recipe.zope2instance