Only do crowfly if we leave the requested area

* If the stop_point is part of the stop_area, then : crow_fly section, no path and no geoJson
* If the stop_point is not part of the stop_area, then : street_network section, with path and geoJson to the centroid of the stop_area

Same principle for admin.

refer to: http://jira.canaltp.fr/browse/NAVITIAII-1093