Document Django 1.7 admin installation changes.

Closes #74.

djrill/__init__.py

@@ -11,7 +11,12 @@ from ._version import *
 MANDRILL_API_URL = getattr(settings, "MANDRILL_API_URL",
     "http://mandrillapp.com/api/1.0")
 
+
 class DjrillAdminSite(AdminSite):
+    # This was originally adapted from https://github.com/jsocol/django-adminplus.
+    # If new versions of Django break DjrillAdminSite, it's worth checking to see
+    # whether django-adminplus has dealt with something similar.
+
     index_template = "djrill/index.html"
     custom_views = []
     custom_urls = []

docs/installation.rst

@@ -88,3 +88,19 @@ If you want to enable the Djrill admin interface, edit your base :file:`urls.py`
             ...
             url(r'^admin/', include(admin.site.urls)),
         )
+
+If you are on **Django 1.7 or later,** you will also need to change the config used
+by the django.contrib.admin app in your :file:`settings.py`:
+
+    .. code-block:: python
+        :emphasize-lines: 4
+
+        ...
+        INSTALLED_APPS = (
+            # For Django 1.7+, use SimpleAdminConfig because we'll call autodiscover...
+            'django.contrib.admin.apps.SimpleAdminConfig',  # instead of 'django.contrib.admin'
+            ...
+            'djrill',
+            ...
+        )
+        ...