The background panels are now static.

I had a lot of code to merely instantiate the pictures which really was
not necessary.
The level indicators are now static on the page.
Merge branch 'ps.remove_dynamic_img_add'

This branch moves a bunch of the dynamic element creation out of app.js
and instead uses elements now created in the HTML source itself.

There's still some work to be done like updating the keg levels at will.