Added command to start datasource

Handy little script to start the datasource with the xcore script itself.  You can currently run it with just `xcore server`.  The logs from the command are written to the console just as if you had run it directly.
If de-coupling is truly your goal, then you'd just invoke `npm start` and not write a lonely script whose sole purpose in life is to spawn `npm start`. Just my $0.02.

I know that this stack you're working with has a lot of craziness in it. One problem we've found is that its tempting to solve craziness with another layer of craziness :)