Previously added some svg versions of icons and background images.
svgs have now been run through svgo and cleaned up per Nikerabbit's
advice.
Also slightly tweaked user.svg to better match raster version.
Change-Id: Icf7ad259366a7051c66e2b8d6ac229ef1f0388fe
Part of the move toward responsiveness.
* Use mixins and variables!
* Vectorise existing icons
* Delete a rule or two that don't apply to the source anymore
* Consolidate similar colours into the same ones using variables
Change-Id: I2f0eb2b79cba01d8fa3a06298711e8af4d5508ba