Fix accepting buffer in stdin.
Fix accepting buffer in stdin.

paulcbetts/node-runas,dbkaplun/node-runas,pombredanne/node-runas,pombredanne/node-runas,dustinblackman/node-runas,dbkaplun/node-runas,atom/node-runas,paulcbetts/node-runas,atom/node-runas,dustinblackman/node-runas