Add new app to handle all dependencies

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/sources/apps.py

@@ -18,6 +18,7 @@ from mayan.apps.navigation.classes import SourceColumn
 from mayan.celery import app
 
 from .classes import StagingFile
+from .dependencies import *  # NOQA
 from .handlers import (
     handler_copy_transformations_to_version, handler_create_default_document_source,
     handler_initialize_periodic_tasks