Workaround launch issue in Windows XP/Python 3

Under Python 3.4 and Windows XP (32 or 64 bit), the spawned process does not inherit stdout/stderr. If the process then tries to spawn its own subprocess, this raises an exception when Python can't make a new file handle. This commit forces subprocess to spawn the new process with inherited file handles, avoiding the issue.

In `subprocess.py` under Windows `close_fds` defaults to `True` unless you pass in at least one of `stdout`, `stderr`, or `stdin`. Presumably then this issue would apply to all Windows versions, but it does not - it happens only on XP (perhaps this is an interpreter issue or there was a change in win32 `CreateProcess` or something)

In particular, this affected launching IPython-Qtconsole. For whatever reason, the behavior only exhibited itself under node-webkit. The exception it raised is: https://gist.github.com/lidavidm/5a05c4eb28ed1c9002d9