fixed bug which was causing deleted craft to not be detected
moved git method out of discover_deleted_craft and into the Repo class
Instance now stores a checksum of the partsDB so it can know when the installed parts have changed
adding a Task object that is like a very simple delayed_job concept. Tasks can be created either in the Interface or System, and will be processed later by system.  Tasks now handle generating part DB for instances and bulk updates of craft part data
Users can disable automatic rebuild of parts DB on load and can also request an rescan of all craft from the instance page.
readme update