added a mock for /bookings GET by returning a manually crafted JSON example
adapted the "from" parameter to "_from" for /bookings/options/ GET both in the booking.yaml and the handler definition to address a reserved word issue ==> we should fix that later
added ReDoc support by adding a staticfile.yaml and the corresponding handler to apiy.py + crerated redoc.htm; added a x-logo section in info: section to booking.yaml