Enhance goods code not being found handling code

This change is for https://www.pivotaltracker.com/story/show/55066242

Adds some intelligent redirects based on search API. E.g.:

* If you try to reach non existing sections redirects to sections listing.
* If you type a wrong heading ID tries to redirect you to a relevant chapter.
* If you access a commodity at date when it did not exist redirects you to actual version.

Things that could be improved, but probably should come as another story (-ies):

* We could show notices/alert why the user was redirected to this particular page. Needs design of the notice. M
* In case we're searching for commodity that does not exist at particular date we could redirect to closest validity period instead of actual version
* We could probably redesign our 404 template to display some tariff-related and meaningful information. Needs design.