add python3 plugin, still missing backend selection and py1/2 crossover
more of the python3 plugin
remove non-src files
first cut at selecting conda environment
In the ipython protocol v1 js, rename IPython to IPython1.  Then in our plugin, use IPython or IPython1 as directed by the version REST call.  This allows us to have both modules loaded simultaneously.  Move the "conda select" from python3Plugin to python2 so that even though it is still hardwired at least the names correspond.
keep short name as "Py"
Merge pull request #858 from twosigma/spot/834

add py3 plugin, make py2 and py3 work simuntaneously