nix extraneous stdio closes; makes debugging hard
fix accidental butchering of stdout/stderr

previously the same FD (master pty) was sent over for both stdout/stderr,
which meant linking would read from the same file in two separate goroutines,
printing to stdout/stderr, leaving the output jumbled and arbitrarily diced
and reordered.

instead, if we're spawning with a tty, send a dummy pipe for stderr, so that
only stdout will receive the data.
set pdeathsig so that child dies when spawn dies
deps
implement resizing tty windows

also, fix stderr of command not being collected when in tty mode
Merge pull request #8 from cloudfoundry-incubator/winsize

implement window resizing, + more tty fixes