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.
There's a link next to it that does the exact same thing and includes
the word "download", which was confusing in some cases since people
might think that links with different texts lead to different pages.
We were rendering the `new` action, but that action doesn't exist.
Before commit ec861ca8e, we were rendering the `edit` action of an
answer, which was confusing as well.
Note that, when adding an invalid document, `@answer.documents` contains
that invalid document (which is not present in the database). Since
we're rendering the index, this new document would appear in the list of
the documents that can be deleted; to avoid that, we're kind of
"reloading" the answer object in the component by finding the record in
the database. We aren't using `@answer.reload` because doing so would
remove the validation errors.
In some cases (e.g. after editing or creating a resource
with errors) the default back_link did not redirect to the
expected page.
Now we force the back_links to the index pages, so we
always get the desired redirect.
