protocol.subscribe should accept callback argument

[jeffbcross]

In the present API, protocol.subscribe only accepts one argument, a binder instance. In the implementation of the subscribe method, the binder has to call binder.onProtocolChange when the data has changed in the protocol. The protocol shouldn't need to know what the method is called, and should accept a callback method instead.

Before:

app.service('myProtocol', function () {
  this.subscribe = function (binder) {
    socket.on('change', function (change) {


      binder.onProtocolChange.call(binder, [change]);


    });
});

After:

app.service('myProtocol', function () {
  this.subscribe = function (binder, callback) {
    socket.on('change', function (change) {


      callback.call(binder, [change]);


    });
});