bdist_wheel fails.

[Bo]

When installing sos-notebook using pip install sos-notebook, there is an error message

installing to build/bdist.macosx-10.9-x86_64/wheel
running install
Checking .pth file support in build/bdist.macosx-10.9-x86_64/wheel/
/Users/bpeng1/anaconda3/bin/python -E -c pass
TEST FAILED: build/bdist.macosx-10.9-x86_64/wheel/ does NOT support .pth files
error: bad install directory or PYTHONPATH

You are attempting to install a package to a directory that is not
on PYTHONPATH and which Python does not read ".pth" files from.  The
installation directory you specified (via --install-dir, --prefix, or
the distutils default setting) was:

    build/bdist.macosx-10.9-x86_64/wheel/

and your PYTHONPATH environment variable currently contains:

    ''

Here are some of your options for correcting the problem:

* You can choose a different installation directory, i.e., one that is
  on PYTHONPATH or supports .pth files

* You can add the installation directory to the PYTHONPATH environment
  variable.  (It must then also be on PYTHONPATH whenever you run
  Python and want to use the package(s) you are installing.)

* You can set up the installation directory to support ".pth" files by
  using one of the approaches described here:

  https://setuptools.readthedocs.io/en/latest/easy_install.html#custom-installation-locations


Please make the appropriate changes for your system and try again.

Checking the documentation, it appears that bdist_wheel is the newer standard. The problem with our setup.py is the use of customized install script that installs the sos kernel to jupyter, which is discouraged by wheel. Actually, as this post suggests, and as other kernels do, we should separate the installation and deployment of the sos kernel.