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/common/api_views.py

@@ -2,9 +2,10 @@ from __future__ import unicode_literals
 
 from django.contrib.contenttypes.models import ContentType
 
-from rest_framework import generics
 from rest_framework.permissions import IsAuthenticated
 
+from mayan.apps.rest_api import generics
+
 from .classes import Template
 from .serializers import ContentTypeSerializer, TemplateSerializer