'tahoe run' should not redirect stdout/stderr

[davidsarah]

<warner>: so first off, any 'print's in the gateway will show up in NODEDIR/logs/twistd.log, not on stdout

<T_X>: ah! okay, I was already wondering whether something gets redirected :)

<warner>: (that's always true when launched with 'tahoe start', but I think it may also currently be true when run with 'tahoe run', although I'd love to fix that)

I don't see print output even in NODEDIR/logs/twistd.log; it just seems to disappear. In any case, this would be very useful for debugging.