SyncRecordsController

When the Provider comes online, there needs to be a controller that pushes all local Record object changes to the elasticsearch database (if they are more recent than the versions on the database).

It should check various conditions like making sure that the record hasn't been deleted by an online user and that the associated problem still exists.

The main thread does not wait on this, it is an AsyncTask launched in the background that goes about the task.

see #252

Start by locating the Record and Provider models and any existing synchronization or AsyncTask entry points. Trace how local changes, deletions, and associated problems are represented before defining the controller's conditions. Done means background synchronization safely pushes only newer records while handling deleted records and missing problems.

Written by the indexing model from the issue text.