fix(defaultKernel): default to py3, py2, then 1st lexicographically
fix(defaultKernel): default to py3, py2, then 1st lexicographically

rgbkrk/nteract,captainsafia/nteract,rgbkrk/nteract,rgbkrk/nteract,jdfreder/nteract,0u812/nteract,jdetle/nteract,nteract/composition,jdetle/nteract,nteract/nteract,nteract/nteract,captainsafia/nteract,rgbkrk/nteract,0u812/nteract,jdetle/nteract,jdfreder/nteract,0u812/nteract,captainsafia/nteract,0u812/nteract,captainsafia/nteract,nteract/nteract,rgbkrk/nteract,jdfreder/nteract,jdetle/nteract,nteract/nteract,jdfreder/nteract,temogen/nteract,nteract/composition,temogen/nteract,nteract/composition,nteract/nteract,temogen/nteract