explicitly mention email address to contact for rejected relays

from the discussion on bad-relays@..

When we reject relays the operator gets to see something like this in their logs:

[warn] http status 400 ("Fingerprint is marked rejected -- please contact us?") response from dirserver 'IP:Port'. Please correct.

Lets change this to:

"Fingerprint is marked rejected, if you think this is a mistake please set a ContactInfo and send an email to bad-relays@lists.torproject.org mentioning your fingerprint(s)"