Add node upgrade to History
Updated skeleton app with a reactive example and changed code style
Update skeleton app

Summary: The current skeleton app hasn't changed in a long time. I changed it to add an example of using the Session variable, and updated the code style to be the recommended Template.hello.helpers() instead of Template.hello.helperName = function () {}

Test Plan: I ran the app and it worked. It's very simple so not much can go wrong.

Reviewers: avital, nim

Reviewed By: avital

Differential Revision: https://phabricator.meteor.com/D754