Added empty cart button

Signed-off-by: Craig Sullivan <craig@melbourne-systems.com>
Merge branch 'master' of github.com:craigs/launchly-cart

Conflicts:
	sample/cart-functions/empty.html

Signed-off-by: Craig Sullivan <craig@melbourne-systems.com>
Updated sample

Signed-off-by: Craig Sullivan <craig@melbourne-systems.com>