add versioning support to the API

src/paperless/settings.py

@@ -112,7 +112,10 @@ REST_FRAMEWORK = {
         'rest_framework.authentication.BasicAuthentication',
         'rest_framework.authentication.SessionAuthentication',
         'rest_framework.authentication.TokenAuthentication'
-    ]
+    ],
+    'DEFAULT_VERSIONING_CLASS': 'rest_framework.versioning.AcceptHeaderVersioning',
+    'DEFAULT_VERSION': 'v1',
+    'ALLOWED_VERSIONS': ['1', '2']
 }
 
 if DEBUG:
@@ -142,7 +145,7 @@ ASGI_APPLICATION = "paperless.asgi.application"
 
 STATIC_URL = os.getenv("PAPERLESS_STATIC_URL", "/static/")
 
-# what is this used for?
+# TODO: what is this used for?
 TEMPLATES = [
     {
         'BACKEND': 'django.template.backends.django.DjangoTemplates',