add lato .woff font files
move icon font declaration into new stylus file
add lato font to font stylsheet
updates homepage stylus
add variables for font-weights
apply new font styles
use colons consistently in stylus
Merge branch 'master' into improve_typography

* master:
  remove errant reference to nonexistent image in homepage mascot svg
  small updates to nav mascot svg
  remove pointless subpixel dimension properties
  remove unused images