Patches to tutorial

The current tutorial shows no server, so a user cannot complete the steps posting JSON by following the instructions.  Also (per issue #603), users get the mistaken impression they need jQuery.  This patch adds sample code for a python server and additional explanations as to what the application expects from a server.
Nit, but single spaces after sentences and other punctuation (you have a mix of 2 and 3).

Still thinking about the best way to actually share the server code.