PulsarCrossCorr_v2: fixed calculation of lowest bin index

  -- Corrected behavior to subrtract f0 before figuring out bin index corresponding to desired frequency.  This was the cause of the array overstepping that was breaking the test script
  -- fixes #1168
re-activated testPulsarCrossCorr_v2.sh after segfault has been fixed

   - closes #1168
cbcBayesPostProc.py: Tweaks to 2D plots for better quality