* single files with all (raw) elections and votes
   - one line = one object
   - intentions:
     + elections are directly served from elections.json
     + new votes are directly appended to votes.json
 * other data (for now, keys and results) are put in separate files
   for each election

FIXME: mysterious segfaults happen in the toplevel, only there and non
deterministically... looks like a bug in Lwt: gdb and "thread apply
all bt" reveal that caml_interprete is running in two threads at the
same time.