CANVAS-32 add sfu branding to canvas

Squahsed commits:

add header-rainbow div in sfu.js

add background images

add sfu.css

add sfu fonts

add help link

remove instructure branding from footer and add sfu logo

use relative urls

add sfu font-family

css font tweaks

add sfu logo

add sfu canvas logo

remove accidental sfu.html file
Merge pull request #13 from grahamb/canvas32-theme

CANVAS-32 add sfu branding to canvas