issue #1020 - One way to make the list/grid controls responsive again

- Changing grid classes through common.js when list/grid controls are clicked.
- Removed some css rendered obsolete by the above.
- Added product-grid class in several tpl files.
  (products are in grid layout by default)
- A few minor tweaks.

The script in common.js worked on the product-grid and product-list classes, which were missing, hence the additions to the tpl files. Extended the same script to change around the grid classes for a row layout.

As it looks like this was kind of a todo after some layout changes, I'm unsure whether this is the best way, so do review with care.