/usr/bin/env: node: No such file or directory

Hi,

Running Ubuntu 14.04 and nodejs 0.10.25~dfsg2-2ubuntu1

The node binary is called `nodejs` (and there is no `node` binary) which makes gulp fail https://github.com/gulpjs/gulp/blob/master/bin/gulp.js#L1

The following would fix it (unfortunately, there is no simpler hack AFAIK):

```

#!/bin/sh
':' //; exec "$(command -v nodejs || command -v node)" -- "$0" "$@"
```

What do you think?
