Add option to configure Application channels

As discussed in #1321. Documentation still to come. 
These tests make sense. 

Small nit-picky thing. We generall don't extract the expects into helper functions. This might seem like more code, but I think a format like:

```js
describe('radio channels', function() {
  describe('with default channel name', function() {
  });
   
  describe('with channel name set as a prototype property', function() {
  });

  describe('with channel name set as a constructor option', function() {
  });
});