OnDemandPhoto can be written differently by overriding __getattr__

I did this recently to cache an RPC call that returned many different fields.

it basically did something like

def _get_remote_info(self):
    if self._remote_info:
        return self._remote_info
    self._remote_info = do_rpc_call_stuff(self.id)
    return self._remote_info
remote_info = property(_get_remote_info)
def __getattr__(self, name):
    if name in ('foo', 'bar','baz','lots','of','fields'):
        return self.remote_info[name]
    ...
    #alternatively: if name in self.remote_info:
    #                   return self.remote_info[name]

This way, if the remote method was changed to return more values, I only had to change one line, or zero if I used the alternate method. The only downside I see to this is that the autogenerated docs for the class won't include any mention of these fields.