Log contents of bw_accounting when we read it; fix memory leak.

  interval_start_time = t1;

  expected_bandwidth_usage = expected_bw;

  log_fn(LOG_INFO, "Successfully read bandwidth accounting file written at %s for interval starting at %s.  We have been active for %lu seconds in this interval.  At the start of the interval, we expected to use about %lu KB per second. ("U64_FORMAT" bytes read so far, "U64_FORMAT" bytes written so far)",

         (char*)smartlist_get(elts,2),

         (char*)smartlist_get(elts,1),

         (unsigned long)n_seconds_active_in_interval,

         (unsigned long)((uint64_t)expected_bandwidth_usage*1024/60),

         n_bytes_read_in_interval,

         n_bytes_written_in_interval);

  SMARTLIST_FOREACH(elts, char *, cp, tor_free(cp));

  smartlist_free(elts);

  return 0;

 err:

  SMARTLIST_FOREACH(elts, char *, cp, tor_free(cp));