Fix OPTIONS responses: Remove all HEAD methods as they return errors. Do not advertise writable method for class/id/properties path if property is read only (i.e. protected prop). Collections do not have PUT, PATCH, DELETE (delete is accepted but always returns 400 code).

try:
    # Python 2.
    my_input = raw_input
except NameError:
    # Python 3+.
    my_input = input