Adding "compile:icons" task for icon generation
Add a margin to prevent sprites leaking into each other
Adding imagemin for image compression
Remove extra code
Precise asset dimensions
Updated docs
Optimised sprite
Fix g+ icon truncation in fallback mode
Merge remote-tracking branch 'origin/master' into icons

Conflicts:
	common/app/assets/images/global/sprite.png
	common/app/assets/stylesheets/theme/_global-icons-sprite.scss
Add imagemin task
Cleaner code
Optimised images
Merge remote-tracking branch 'origin/master' into icons
Remove styleguide references
Update image hashes
Merge pull request #1730 from guardian/icons

Sprite Generator fixes