Change source of ftw.simplelayout, ftw.publisher.core
ftw.publisher.core was released with the necessary changes. Therefore
we can use it from pypi now. ftw.simplelayout still has the unreleased
commit https://github.com/4teamwork/ftw.simplelayout/commit/5533a3a2cb9fee8748308e294d1735d38f11d026
which we need but the it was merged to master. That means that we can't use
the latest release but have to use the master branch.