Switching field at /cultivations redirects to the wrong page

[SvenVw]

When at the "Gewassen" page of a field and you use the header to switch from field the redirect is providing the wrong url with the cultivation id included from the other field. This results into that the card with the cultivation details is not updated and shows the wrong information.

For example, the page farm/[b_id_farm/[calendar/field/[b_id]/cultivation/[b_lu] redirects to farm/[b_id_farm/[calendar/field/[b_id2]/cultivation/[b_lu], instead of farm/[b_id_farm/[calendar/field/[b_id]/cultivation

[SvenVw]

As this especially is required for #191, I will include it that branch