[#135] Explicitly set urlconf in middleware.py

Use the set_urlconf() function from django/core/urlresolvers to set the
correct urls file for RSR and partner sites respectively.
[#135] Re-direct non-authenticated users to sign-in when adding an update

When accessing the project update form the user is now re-directed to
sign-in if not logged in. After signing in the user is returned to the
project update form.
[#135] Hide "Add update" button to non-connected users

On partner site project pages, when a user is logged in hide the "add
update" button if the user is not connected to the current project.