This is mostly working, but not completely ideal for two reasons.

1. Rather than emitting an error on the ChildProcess object when the
setgid/setuid fails, it is simply printing the error to stderr and
exiting.  The same happens with the cwd, so that's not completely
terrible.

2. I don't have a good test for this.  It fails with an EPERM if you try
to change the uid or gid as a non-root user.

Also is run in its own session.

path.split() no longer available

But only after control has been inverted.

results in slow bench

Because path.resolve is more elegant and windows-safe.

Removes path.normalizeArray() and path.split()

It breaks argv[0] on posix systems, and makes it so that npm can't
determine whether node was run from an explicit location, or via "node",
so the configs default improperly.

If on windows, don't do this behavior.  On posix, go back to the old
behavior.

Towards windows compatibility.

Now the path module can be adapted to support windows paths without breaking
the url module.  It also allows the undocumented keepBlanks flag to be
removed from path.join and path.normalizeArray.

This reverts commit 131546e7.

Doesn't work on windows, coming back soon.

Conflicts:
	src/node.cc
	src/node.js