Adds and uses a modified_by property in models/work.py
This property is used to display the user who last edited the work in the document viewer.
Fixes author being set on every edit.
Also edited the style-sheet to fix issue i128.
Patch by: Lennard de Rijk
"""Multi-consumer multi-producer dispatching mechanism
Originally based on pydispatch (BSD) http://pypi.python.org/pypi/PyDispatcher/2.0.1
See license.txt for original license.
Heavily modified for Django's purposes.
"""
from django.dispatch.dispatcher import Signal