Tied django-livesettings commit

Created by: martinburchell

I haven't fully investigated this yet but a couple of people have reported a RECURSIVE_RELATIONSHIP_CONSTANT error in actionitems.

This seems to be due in part to an incompatibility with the latest version of django-livesettings, which is generating an error about config_register not being imported in publicweb/config.py. At some point we're going to need to change this to:

from livesettings.functions import ...

The quickest fix is to tie our version of livesettings to a working commit. This is probably good practice anyway.