Better client branding + place holder text

Add more options for client branding like a logo on top of a gallery that also becomes the favicon and make it possible to hide the “Main Gallery / Sub Gallery” labels or the asset count. In short a more client focused approach with projects instead of galleries and sub galleries.

Would also be nice to have a place holder text for each subgallery attached to a template. That way it can contain a basic message or instructions for each project.