Updated to Spree 2.4

* Finished filters partial.
* Some misc style fixes.
Commit for uploading. Too many changes for one line. :)

* MAJOR refactoring. Added partials and a couple of helper methods. (still some refactoring pending)
* Added some missing sections.
* Added destinations and thing-to-do views. For now, destinations are products that cannot be bought.
* And many, many other changes... mostly towards COC and DRY.