Update footer with current affiliations

[rhiju]

As I'm less active with Dept. of Physics, and Bio-X Games Center is defunct, let's remove the two logos for those.

And let's add the HHMI logo, linking to https://www.hhmi.org/scientists/rhiju-das

Here's the link to the logo:

https://www.hhmi.org/sites/default/files/Logos/JPG/HHMI-logo-color.jpg

[tkaragianes]

All of the ui chrome elements (nav bar, footer icons, etc) appear to be in a spritesheet, and then referenced with background-position. Not very flexible, and not responsive. This should be changed to inline the images.