Support multiple usages of Reflux.connect on the same react components.

Recent changes in Reflux.connect makes this impossible.

__Example use case:__
```Javascript
var Layout = React.createClass({
    mixins: [
        Reflux.connect(MenuStore, "menu"),
        Reflux.connect(FriendStore, "friends"),
        Reflux.connect(RouteStore, "route"),
    ],
    render: function () {
        return (
            <div id="layout">
                <Menu items={this.state.menu.items}/>
                <Friends items={this.state.friends}/>
                <Content items={this.state.route.view}/>
            </div>
        );
    }
});
```