Sidebar Image Loading and Organization

@gadomski, I've standardized the image size for the sidebar images, and
have created both full-color and black & white versions. I think we can
assign a selection of these images to each individual page, but I tried
to make them general enough to just use a random choice at each page
load.
Fix of sensor names
Fix image filenames

Remove spaces and fix case sensitivity.

@adamlewinter note that filenames can't (reliably) have spaces in them
if we want to use them on the web. Also, filenames are case sensitive,
so .jpg and .JPG are different.

Fixes #88.
Move chart files out of subdirectory

We're going to use fetch in other scripts.
Stash
Add less and coffee
Stash