usertips misc changes (including a couple of fixes)
Markdown syntax for usertips (consistently with the readme)
bugfix: computation (and then saving) of default directory state resulting in a wrong saved data format fixed.
Bugged function wasn't (and currently isn't) under test coverage.

{<username>: (<timestamp>, <server_state>), ...}
fixed to:
{<username>: {'server_timestamp': <timestamp>, 'files': <snapshot>}, ...}
(m) cleanup of unused variables