fix lxml bug

related to parsing unicode strings that also have an encoding/charset definition in the XML opener
Use pdb.post_mortem instead of pdb.set_trace in debug utility.
Correctly spawn greenlets using retry_wrapper.

retry_wrapper executes its function argument, instead of returning a wrapper
function object. So we have to do gevent.spawn(retry_wrapper, func), not
gevent.spawn(retry_wrapper(func)).
Redis configuration + setup.
Bootstrap Redis account sync status info.
Update Redis account sync status info on start-up.
Fix state reporting in report_progress() -> Update folder sync status info.
Calc num_local_updated, num_local_deleted.
Redis schema for per-folder sync status info.
Bootstrap per-folder sync status info.
DB schema changes (FolderSync tables) + migration.
Include timestamp in folder sync status info.
Script for Redis server.
Minor fixes.