Using the `document` or `documents` classes meant styles defined for the
public list of documents conflict with these ones.
So now we're using HTML classes that match the name of the Ruby
component classes, as we usually do.
We were adding <div> tags with the `images` or `documents` HTML class
prettly much every time we rendered a NestedComponent. We're now
including the HTML class inside the component, as we usually do.
We're also rendering the nested components directly, since it's been a
while since the partials were changed to simply render the components.
These labels weren't associated with any fields, which is invalid HTML.
We're using a legend inside a fieldset instead, which is the natural way
to group form fields together.
