Introduction of small logo

Introduce a small logo branding value that can be used to configure a small institutional logo that's shown on small screens. It seems like at least `480x320` and `600x800` could be using this. We should investigate if we can get the smallest layout to show this as well.

Dropping the search icon from the logged out view is an option as well.

The default OAE small logo can be the OAE logo `O`