Remove remnants of edumanage/middleware.py

Leftover from before switching to Python Social Auth. The actual
middleware had been removed in 017e8975

edumanage/middleware.py

-from django.conf import settings
-from django.core.urlresolvers import RegexURLResolver
-
-
-def resolver(request):
-    """
-    Returns a RegexURLResolver for the request's urlconf.
-
-    If the request does not have a urlconf object, then the default of
-    settings.ROOT_URLCONF is used.
-    """
-    urlconf = getattr(request, "urlconf", settings.ROOT_URLCONF)
-    return RegexURLResolver(r'^/', urlconf)