Drop optimist from the dev bundle

The tool no longer uses it.  Simplify webapp_server to do a dumb check
for a flag instead of using optimist.

ctl-helper still uses optimist; ideally it should use our parser from
main.js instead.

Also, remove a debugging "|| true" that was causing "LISTENING" to be
output even without --keepalive.

I am not actually planning to rebuild the dev bundle just to drop
optimist.