'Fetch and return all the routes associated by JupyterHub from the
proxy.
**Subclasses must define this method**
Should return a dictionary of routes, where the keys are
routespecs and each value is a dict of the form::
\'routespec\': the route specification ([host]/path/)
\'target\': the target host URL (proto://host) for this route
\'data\': the attached data dict for this route (as specified in add_route)'

@gen.coroutine
def get_all_routes(self):

    pass
