Jupyter deprecations

[ViralBShah]

[TerminalIPythonApp] WARNING | Subcommand `ipython kernelspec` is deprecated and will be removed in future versions.
[TerminalIPythonApp] WARNING | You likely want to use `jupyter kernelspec` in the future

[yuyichao]

I think you most likely have an old IJulia or a stale IJulia install. Fresh install shouldn't have this problem and I don't think removing IPython configure file (or removing files that are not in pkgdir in general) during upgrade is a good idea. We could potential give a warning and let the user to remove the file manually though.

[ViralBShah]

I had done Pkg.update(), before getting this.

[stevengj]

The problem is that IJulia build script "remembers" your old jupyter command. On your machine, it is remembering that you used ipython. rm(Pkg.dir("IJulia","deps","JUPYTER")) and re-run Pkg.build("IJulia").

[ViralBShah]

Thanks. That also explains why I haven't seen this on machines where I installed recently. This indeed did fix it.

[ViralBShah]

I now get this (even after removing IJulia completely from my .julia and reinstalling):

INFO: Found Jupyter version 4.1.1: jupyter
Writing IJulia kernelspec to /Users/viral/.julia/v0.5/IJulia/deps/julia-0.5/kernel.json ...
Installing julia kernelspec julia-0.5
jupyter: 'kernelspec' is not a Jupyter command
===============================[ ERROR: IJulia ]================================

LoadError: could not spawn `jupyter-kernelspec install --replace --user /Users/viral/.julia/v0.5/IJulia/deps/julia-0.5`: no such file or directory (ENOENT)
while loading /Users/viral/.julia/v0.5/IJulia/deps/build.jl, in expression starting on line 100

================================================================================

================================[ BUILD ERRORS ]================================

WARNING: IJulia had build errors.

 - packages with build errors remain installed in /Users/viral/.julia/v0.5
 - build the package(s) and all dependencies with `Pkg.build("IJulia")`
 - build a single package by running its `deps/build.jl` script

================================================================================

[stevengj]

Related to #363 and jupyter/jupyter_core#62? Can you open a new issue with info about your system?