Fix/improve npm test compatibility on windows

Add some changes to enable Windows users to run `npm start` and `npm test`.
(It still relies on `node` and `java` being available in the environment PATH.)
On my Windows machine, using npm, I've got the following node_modules/.bin/minijasminenode file:

```bash
#!/bin/sh
basedir=`dirname "$0"`

case `uname` in
    *CYGWIN*) basedir=`cygpath -w "$basedir"`;;
esac

if [ -x "$basedir/node" ]; then
  "$basedir/node"  "$basedir/../minijasminenode/bin/minijn" "$@"
  ret=$?
else
  node  "$basedir/../minijasminenode/bin/minijn" "$@"
  ret=$?
fi
exit $ret
```

This shell file was created by npm and is used to call `minijasminenode/bin/minijin` from the minijasminenode folder.

So calling it with `node` will not work.

Does npm creates a node-compatible script on Linux?