Use V3BwHeader to generate the header

sbws/core/generate.py

 from sbws import version
 from sbws.globals import (fail_hard, is_initted, time_now)
+from sbws.lib.v3bwfile import V3BwHeader
 from sbws.lib.resultdump import ResultSuccess
 from sbws.lib.resultdump import load_recent_results_in_datadir
 from sbws.lib.resultdump import group_results_by_relay
@@ -120,10 +121,10 @@ def main(args, conf):
     data_lines = [result_data_to_v3bw_line(data, fp) for fp in data]
     data_lines = sorted(data_lines, key=lambda d: d.bw, reverse=True)
     data_lines = scale_lines(args, data_lines)
+    header = V3BwHeader()
     log_stats(data_lines)
     log.info('Writing v3bw file to %s', args.output)
     with open(args.output, 'wt') as fd:
-        fd.write('{}\n'.format(int(time_now())))
-        fd.write('version={}\n'.format(version))
+        fd.write(header)
         for line in data_lines:
             fd.write('{}\n'.format(str(line)))