Switch pretty much all references to cleartext in modules/engines/ to just use the record. Also clean up some references to null cleartext to use deleted. The only reference to cleartext is to iterate over that hash in bookmarks.
Expose a .deleted property that engines can set to true to store an even thinner deleted payload (empty string "" instead of "[null]") on the server. Handle deserializing of deleted records by setting the property. Note: Engines must set their payloads to something JSON-able if it's not a delete record.
* some minor hacking of the login progress to improve performance
* expanded the application exit sync dialog to be a general modal sync dialog that will display whenever appropriate (e.g. during initial setup, on manual "sync now" requests, and on application exit)
* added a progress meter and status messages to the modal sync dialog to provide users with a better understanding of what's going on, and to assist in debugging
* added ability to cancel a modal sync request, including on application exit. when cancel is clicked on by the user, it will attempt to cancel the sync at the next opportunity (i.e. before the next sync engine is processed)
