do not take self advertised bandwidth into account

1. It might result a long-term up and down of relay bw. Imageing a case, where for some reason a relay reports a lower traffic. It will get a lower weigth which yields into lower traffic and so on.

2. It invites people to manipulate the weight of their relays.

BTW: In IRC there are hints and tipps flying around how and where to change the Tor source code to manipulate the transferred traffic.