Added rel="external" icon
Making sure rel="external" icon doesn't bleed into share widget
Icon sprite updated
Make sure external icon doesn't appear in header, footer or left menu
Formatting changes to SCSS files re: external icon
spacing issues fixed in scss file
Merge branch 'v3.0' of https://github.com/cfarquharson/wet-boew into cfarquharson-v3.0
Limited scope of external icon to wb-main (instead of applying everywhere and overriding for certain sections). Fixed support for grids button (all four sizes). Fixed external icon working example.