Pass in parameters to the driver in stdin rather than through argv.
This allows us to more easily route parameters to the driver and add
more parameters without breaking users. The driver doesn't need to
have the same interface as go list, because it's unlikely the driver interface
will converge with the go list interface.
We still pass in the query "words" to the driver in the argv, because
that's as good a place as any, but there's no "list" command.
Question: should we add a "command" option to the driverRequest struct?
Change-Id: Ifdbb3f84b6bfd04259f5ab63e756341d7f69de9b
Reviewed-on: https://go-review.googlesource.com/c/150337
Reviewed-by: Ian Cottrell <iancottrell@google.com>