Adds possibility of having children for custom components

This PR adds the functionality of having Components as children of Omniscient components, like so:

```js
var Comp = component(function (cursor) {
   // this.props.children[0] === h1 element
});

var App = component(function (cursor) {
   return Comp(cursor.get('item'), React.DOM.h1(null, 'Hello'));
});
```

We should decide if this is a change we want or not. Is this the direction we want to go in?

(Cleaned up branch/PR)