o Minor bugfixes (Testing networks)
    - Stop requiring exits to have non-zero bandwithcapacity in a
      TestingTorNetwork. Instead, when TestingMinExitFlagThreshold is 0,
      ignore exit bandwidthcapacity.
      This assists in bootstrapping a testing Tor network.
      Fixes bugs parts of bugs 13718 and 13839;
      Makes bug 13161's TestingDirAuthVoteExit non-essential.
      Bugfix on 0.2.0.3-alpha.