Use React 0.14's stateless components

[rolyatmax]

Some spots where we could use React 0.14's stateless components.

depends on #79

[rolyatmax]

@AlanFoster Let me know what you think of this.

[AlanFoster]

I'm a fan of the newer notation; But we should be consistent with the rest of the code base. Particularly since this will make it harder for us to add propType and defaultPropType information in the future if we need to. Likewise newcomers to React may not fully appreciate the terseness of this PR change.

I'll close this PR for now, but we might re-visit it in the future!

[rolyatmax]

Do you mean that to use React's stateless functions syntax, we would need to use only stateless components in order to be consistent?

Or do you mean we should be consistent with how we define stateless components?:

const Link = ({href, text}) => <a href={href}>{text}</a>;

// versus

function Link({href, text}) {
    return <a href={href}>{text}</a>;
}

Also, for what it's worth, you can add propType validation like so:

function MyComponent({children}) {
    return <div>{children}</div>;
}

MyComponent.propTypes = {
    children: React.PropTypes.node.isRequired
};

[rolyatmax]

If we don't want to move ahead with this PR, should we pull this change out and merge separately?