Add support for reindexing document on content parsing changes.

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

mayan/apps/document_parsing/signals.py

@@ -0,0 +1,7 @@
+from __future__ import unicode_literals
+
+from django.dispatch import Signal
+
+post_document_version_parsing = Signal(
+    providing_args=('instance',), use_caching=True
+)