Update cabinets and document_index api views docstrings. Update multi level docstrings as per Python best practices.

Signed-off-by: Michael Price <loneviking72@gmail.com>

mayan/apps/document_indexing/api_views.py

@@ -56,7 +56,6 @@ class APIIndexNodeInstanceDocumentListView(generics.ListAPIView):
     Returns a list of all the documents contained by a particular index node
     instance.
     """
-
     filter_backends = (MayanObjectPermissionsFilter,)
     mayan_object_permissions = {'GET': (permission_document_view,)}
     serializer_class = DocumentSerializer
@@ -105,7 +104,6 @@ class APIDocumentIndexListView(generics.ListAPIView):
     """
     Returns a list of all the indexes to which a document belongs.
     """
-
     filter_backends = (MayanObjectPermissionsFilter,)
     mayan_object_permissions = {'GET': (permission_document_indexing_view,)}
     serializer_class = IndexInstanceNodeSerializer

mayan/apps/document_indexing/views.py

@@ -291,7 +291,6 @@ class DocumentIndexNodeListView(SingleObjectListView):
     """
     Show a list of indexes where the current document can be found
     """
-
     object_permission = permission_document_indexing_view
     object_permission_related = 'index'
 

mayan/apps/document_indexing/widgets.py

@@ -10,7 +10,6 @@ def get_instance_link(index_instance_node):
     """
     Return an HTML anchor to an index node instance
     """
-
     return mark_safe(
         '<a href="{url}">{text}</a>'.format(
             url=index_instance_node.get_absolute_url(),
@@ -45,7 +44,6 @@ def node_level(node):
     """
     Render an indented tree like output for a specific node
     """
-
     return mark_safe(
         ''.join(
             [