What's new in this release:

IMPORTANT CHANGES

• The histogram API has changed significantly! Bins are 0-indexed at the
  underflow bin like ROOT and now offer full slicing support. This change is
  not backward compatible so please be careful when updating to the latest
  rootpy and be sure that you migrate the use of histograms in your code. See
  the pull request for more
  details.
• Moved rootpy.batch to a separate project

General improvements

• ROOT 6 support
• Partial support for Python 3
• Expanded HistFactory/RooFit/RooStats coverage
• Many others improvements...