fix thinko in unit tests
remove obsolete test

the server bumps the modtime prior to download these days because it has to
update the usn
move sanity check to server and automatically force full sync

- server will log mismatches so we don't require people to post on the forums
  anymore or manually force a full sync
- if we find problems like missing notes, report that in the sanity check so
  the server can keep track of problems
- when the server detects a conflict it can immediately abort the sync, so a
  subsequent sync will no longer report a conflict