Add shared cache class and add mounted index cache invalidation when document and index instance nodes are updated or deleted.

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

mayan/apps/mirroring/handlers.py

@@ -0,0 +1,11 @@
+from __future__ import unicode_literals
+
+from .runtime import cache
+
+
+def handler_document_cache_delete(sender, **kwargs):
+    cache.clear_document(document=kwargs['instance'])
+
+
+def handler_node_cache_delete(sender, **kwargs):
+    cache.clear_node(node=kwargs['instance'])