Actions from children

This PR allows to perform actions on a component when a specified nested component has triggered an action too.

Consider the following nested components:
```
parent
  |_ demoChild
```

The syntax is:

```javascript
//child component named 'demoChild'
Hull.component({
  actions: {
    "doSomething": function () {console.log("I'm the child");}
  }
});

//parent component
Hull.component({
  actions: {
    "demoChild.doSomething": function () {console.log("My child did something");}
  }
});
```

The signature for the actions has been updated as follows:

```javascript
function (event, context, component) {}
```

to support this new feature. In 'normal' actions, the `component` arg is like `component === this`.


Whenever the `demoChild` component triggers `doSomething`, the parent receives it. If no handler is defined in the parent, nothing happens.