Changes to model in compose bindings doesn't call the activate method.

[Souldrinker]

When using string based view-model in a compose binding the activate method of the composed view doesn't get called when the model of the composed binding changes.

The modelChanged method of compose.js looks like this:

    modelChanged(newValue, oldValue){
        if(this.viewModel && typeof this.viewModel.activate === 'function'){
            this.viewModel.activate(newValue);
        }

So if you use string based view models the check for an activate function always fails and thus the activate isn't triggered as expected (and as it does in Durandal).

Some more details about this issue can be found in todays (2015-02-11) Gitter chat between me and @zewa666 or here: https://github.com/Souldrinker/compose-issue