Add rename_app command and use it

This allows users to migrate from a pre-rename database without
resetting their database, hopefully

bookwyrm/settings.py

@@ -40,6 +40,7 @@ INSTALLED_APPS = [
     'django.contrib.messages',
     'django.contrib.staticfiles',
     'django.contrib.humanize',
+    'django_rename_app',
     'bookwyrm',
     'celery',
 ]

fr-dev

@@ -48,6 +48,7 @@ case "$1" in
         execweb python manage.py makemigrations
         ;;
     migrate)
+        execweb python manage.py rename_app fedireads bookwyrm
         execweb python manage.py migrate
         ;;
     bash)

requirements.txt

@@ -14,3 +14,4 @@ python-dateutil==2.8.1
 redis==3.4.1
 requests==2.22.0
 responses==0.10.14
+django-rename-app==0.1.2