VID-1946 Create gallery controller for gallery thumbs

Yes, it does. The first 3 images in the page are not lazy loaded and render without error. There are also other members which never get set for galleries (imgWidth and imgHeight are 2 examples), and mustache handles them gracefully. The docs say ```A {{name}} tag in a basic template will try to find the name key in the current context. If there is no name key, the parent contexts will be checked recursively. If the top context is reached and the name key is still not found, nothing will be rendered.```. All of these members are first defined in section tags which seem to follow this same rule.