Reportback modal

* Opens modal after user uploads a file
* First pass at modal styles
* Allows user to enter a caption

@weerd @DFurnes 
So this is a bit nit-picky, but I'd recommend that the name for this "image cropping" module be the top level class name, and ".wrapper"s sit inside of it. It's more of the pattern we've been doing across modules in the site instead of going for the whole "wrapper" sits outside of everything and kind of muddies the naming.

So maybe something like:

`````
<div class="image-cropper">
  <div class="image-editor">
    <div class="__buttons">
      ...
    </div>
  </div>
</div>