Parser to check if component accepts children

[zachintosh]

We need a parser that somehow checks if a component accepts children. React-docgen does not pick up if it uses children unless listed as a prop-type, for some reason.

This would be easiest to use if it added a boolean to the component meta for whether or not it accepts children.

This way we can tell if we need an edit button for children, even if they don't list it in the props.

[kyle-west]

Sweet. Yeah I'll take it.