added Source Sans font and Header Stanford logo
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-retinize-2155
retinize footer stanford logo
changed header stanford logo to html img tag
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-retinize-2155
commented out sticky footer for now
Merge remote-tracking branch 'origin' into giulio-retinize-2155

Conflicts:
	main/c2g/static/css/core/body.css
	main/templates/base.html
Merge pull request #2159 from Stanford-Online/giulio-retinize-2155

Retinize header and footer default sans serif font