Upgrade to Django 1.6

* The TransactionMiddleware is deprecated and replaced by the ATOMIC_REQUESTS
  field in the database configuration. This is basically the same, but there are
  two differences: 1. one cannot switch between commit and autocommit within a
  view anymore (CATMAID didn't make use of this) and 2. ATOMIC_REQUESTS only
  applies to views. TransactionMiddleware applied to all middleware classes
  coming after it in the list (CATMAID didn't make use of this,
  TransactionMiddleware was last).
* Updated the manage.py code to the currently recommended format.
* Updated django-taggit to its recent version to be compatible with Django 1.6.
  This application started using South. Therefore, the first migration of them
  have to be faked (see below).
* Update django-guardion to version 1.1.1, because it didn't support Django
  1.6 before.
* Update django-adminplus to version 0.2.1, because it didn't support Django
  1.6 before.
* Update django-devserver to git version after 0.7.0, because it caused an
  infinite recursion in Django 1.6 before:
  https://code.djangoproject.com/ticket/21348
* Update South to version 0.8.4, because it didn't fully support Django 1.6
  before.
* Update django-celery to version 3.1.1 and celery to version 3.1.7, because
  they didn't fully support Django 1.6 before.

To migrate the database, you have to do the following:

1. Activate the virtualenv
2. ./manage.py syncdb
3. ./manage.py migrate taggit --fake 0001
4. ./manage.py migrate

Your settings.py file needs a new setting called ALLOWED_HOSTS. Please add it
manually or re-run the create_configuration.py script. It is a list of allowed
hosts that a tested agains a request's Host header. More Info can be found here:
https://docs.djangoproject.com/en/1.6/ref/settings/#std:setting-ALLOWED_HOSTS

ALLOWED_HOSTS = ['CATMAID_SERVERNAME']