refactor applications graph
tweak graph styling
add stack graph component
Merge pull request #47 from alphagov/stack-component

Add 'stack' graph component, use on overview page graph
Merge branch 'master' into ui-tweaks4

Conflicts:
	app/assets/javascripts/licensing/views/applicationsgraph.js
	app/assets/javascripts/licensing/views/applicationsperlicencegraph.js