Jupyter notebook with Python 2 and Python3 Kernel

1. Make sure you have pip version greater than 9.0

$ python2 -m pip --version

2. Then do this

$ python2 -m pip install ipykernel OR python2 -m pip install ipykernel --user
$ python2 -m ipykernel install --user

3. Start or restart Jupyter and you should be done.

This solution is from the ipython docs by the way.