Update API.py

[StefaanBatsele]

Updated RecycleApp class for Belgian zip-codes and streets

[pippyn]

Why is this change needed? The current implementation of RecycleApp is working fine for all addresses I have to test with

[Emmanuel-Paulus]

There is problem with some postcode after the change of citys this year.
ex: 2150 Borsbeek become 2150 Antwerp and give now 2 postcode id's (old and new)
Simple change in API.PY row 1288 (last result instead of first)
jsonItems = response.json()['items']
self.postcode_id = jsonItems[len(jsonItems) - 1]['id']