Upgrade Django - Post 1.5 / Pre 1.6 Steps

[adriancollier]

Second task from #544

• Add ALLOWED_HOSTS setting. This might prove a little tricky for partner sites with CNAMEs.
• We use django.contrib.markup that's being deprecated. So another way of managing markdown must be implemented.
• Use the {% verbatim %} template tag. We don't have much javascript templates, but can check them to see if the verbatim tag can be of use.
• Remove all instances of the SMS code including the templates from My Akvo.

[KasperBrandt]

Django upgraded to 1.6..