Migrate journey to new /v2/journey.plan API call

[mvl22]

The journey planning needs to be migrated to the CycleStreets API V2:
http://www.cyclestreets.net/api/v2/journey.plan/
and the retrieval using
http://www.cyclestreets.net/api/v2/journey.retrieve/

at
https://github.com/cyclestreets/mobileweb/blob/master/js/cyclestreets.js#L674