Add travis-ci status image to README.rst
Add travis-ci status image to README.rst

http://about.travis-ci.org/docs/user/status-images/

ndawe/rootpy,kreczko/rootpy,kreczko/rootpy,ndawe/rootpy,rootpy/rootpy,rootpy/rootpy,rootpy/rootpy,ndawe/rootpy,kreczko/rootpy