Fix for #6 and #8

Ensure you now can click labels for checkboxes og radiobuttons to select
and using unique values.
Some small changes to markup and styled with icons for v7 to make links
more clear.
Initialized "Discount codes" and "Unused discount codes" with 0 before
any is added.
It would be better to move these styles to a separate css file and keep the markup cleaner.