tor/changes/bug2081_followup

  o Minor features (authorities)
    - Directory authorities now reject relays running any versions of
      Tor between 0.2.1.3-alpha and 0.2.1.18 inclusive; they have
      known bugs that keep RELAY_EARLY cells from working on rendezvous
      circuits.  Followup to fix for bug 2081.
    - Directory authorities now reject relays running any version of Tor
      older than 0.2.0.26-rc.  That is the earliest version that fetches
      current directory information correctly.  Fix for bug 2156.