Update travis config.
Update travis config.

Make sure our main benchmarks are exercised at least once.
This doesn't give even remotely accurate information, because all
reported numbers are completely dominated by setup and one-time costs,
but makes sure things compile and makes sure the fixtures match.

Update to go 1.12 at the same time.  This is necessary, because making
the benchmarks exercisd is only reasonable in conjunction with the use
of the "-benchtime=1x" flag, which was fairly recently introduced.

Use less of goad script while I'm at it.  I mostly use
https://github.com/warpfork/gof/ now.

polydawn/refmt,polydawn/refmt,polydawn/go-xlate,polydawn/go-xlate