API updates

- Move all generic API classes definitions to the rest_api.generics
module.
- Update API status code on insufficient access for the apps:
indexes, parsing, documents, metadata, ocr, permission,
user management.
- Update API tests.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/django_gpg/api_views.py

@@ -1,9 +1,6 @@
 from __future__ import absolute_import, unicode_literals
 
-from rest_framework import generics
-
-from mayan.apps.rest_api.filters import MayanObjectPermissionsFilter
-from mayan.apps.rest_api.permissions import MayanPermission
+from mayan.apps.rest_api import generics
 
 from .models import Key
 from .permissions import (
@@ -17,10 +14,8 @@ class APIKeyListView(generics.ListCreateAPIView):
     get: Returns a list of all the keys.
     post: Upload a new key.
     """
-    filter_backends = (MayanObjectPermissionsFilter,)
     mayan_object_permissions = {'GET': (permission_key_view,)}
     mayan_view_permissions = {'POST': (permission_key_upload,)}
-    permission_classes = (MayanPermission,)
     queryset = Key.objects.all()
     serializer_class = KeySerializer
 
@@ -30,7 +25,6 @@ class APIKeyView(generics.RetrieveDestroyAPIView):
     delete: Delete the selected key.
     get: Return the details of the selected key.
     """
-    filter_backends = (MayanObjectPermissionsFilter,)
     mayan_object_permissions = {
         'DELETE': (permission_key_delete,),
         'GET': (permission_key_view,),