Add visual design guidelines for Firefox OS
Bugs 870998 872747 8873482 872747 884424 863160 889293 885818
Merge branch 'bug-870998-firefoxos-type' into demo3

Conflicts:
	bedrock/styleguide/templates/styleguide/products/firefox-os-backgrounds.html
	bedrock/styleguide/templates/styleguide/products/firefox-os-buttons.html
	bedrock/styleguide/templates/styleguide/products/firefox-os-headers.html
	bedrock/styleguide/templates/styleguide/products/firefox-os-switcher.html
	bedrock/styleguide/templates/styleguide/products/firefox-os-typeface.html
	bedrock/styleguide/urls.py
	media/css/styleguide/products-firefox-os.less