Attempt to support system-components

[sapegin]

Support components created with factory functions, like system-components:

import system from 'system-components';
const Foo = system({
  is: 'button'
}, 'space');
Foo.propTypes = {};
export default Foo;

This partially fixes #239

Will also require changes in react-docgen-annotation-resolver.

[okonet]

That’s amazing! Thanks Artem!!!