Use kwargs in the url templatetags

Currently it is somewhat impossible to easily customize the url layout since the 
templates don't use kwargs for the url template tags:

For example:

    {% url 'catalogue:detail' review.product.slug review.product.id %}

This requires that the product id is always after the slug, making urls like '{{ id }}-{{ slug }}' impossible.

The solution would be:

    {% url 'catalogue:detail' slug=review.product.slug product_id=review.product.id %}