put test improved (check also that file content and userdata md5 change)
(m) TODO added
server userdata bugfix in put
create a not-empty user directory in tests (use the server default one)
Added a first test for userdata consistency after several actions (see issue #13)

NB: don't cover all actions (issue not closed)
added assert that chech that a deleted path is not in the userdata user dict after the delete
Merge branch 'master' of github.com:corso-python-prato/share-system-team2