transport 6.x-1.0-alpha10

Changes since 6.x-1.0-alpha9:

• #1253086 by joachim: Removed entity_processed_list property from the controller class and reimplemented check with database query.
• #1253112 by joachim: Removed hardcoded node id in debug module.
• #1252086 by joachim: Fixed controller object reference being serialized in the entity handler storage.
• #1252080 by joachim: Added better logging.
• #1247266 by joachim: Added placeholder docblocks for all phase handlers to base class.
• by joachim: Removed mention in documentation of obsolete phase.

Of particular note is #1253086: remove entity_processed_list on the controller, which fixes a memory leak on large (300+) imports made with UpRPC.