Improve error handling during soledad initialization in client
Right now, several exceptions are triggered at several points during soledad initialization, resulting in somehow obscure errors. The load_and_sync is one big, atomic operation from the debug logs' point of view.
The aim is to fragment the soledad boostrapping code to make easier to debug soledad init and sync bugs.
(from redmine: created on 2013-09-27, closed on 2013-10-02, relates #3619 (closed), relates #3867 (closed))