Add conda 4.4+ support (conda not on path errors)

[tjd2002]

Uses the $CONDA_EXE environment variable to find conda, rather than assuming it's on the path. Inspired by (and fixes the same problems as: anaconda/nb_conda_kernels#79 )

Also adds Travis testing for new- and old-style installs (borrowing from: anaconda/nb_conda_kernels#82 and anaconda/nb_conda_kernels#83)

Discussion of 4.4+ support across all nb extensions at: https://github.com/Anaconda-Platform/anaconda-nb-extensions/issues/168

[tjd2002]

@mcg1969 @benbovy could you take a look?

[tjd2002]

(This also incorporates #74 to get tests passing again)

[coveralls]

Coverage decreased (-0.2%) to 45.477% when pulling 65cda30 on tjd2002:conda44-fix into c27196f on Anaconda-Platform:master.

[coveralls]

Coverage decreased (-0.2%) to 45.477% when pulling b1f2498 on tjd2002:conda44-fix into c27196f on Anaconda-Platform:master.

[tjd2002]

Added @voidworker's fix from #66, which handles new behavior of conda info --json since 4.4

[elgalu]

Hi @tjd2002 how is your fork doing?

Given this project doesn't seem maintained I was thinking about switching to your branch but maybe you faced new issues and no longer using nb_conda ?

[BharatKambalur]

Has there been any progress merging this in?

[tjd2002]

I would like to see this merged, but I don't use the conda tab anymore. (I think that Anaconda Navigator is the recommended way to manage conda envs if you need a GUI).

Note that you can still use conda kernels with Jupyter by installing the nb_conda_kernels package.

[tjd2002]

@mcg1969 Any interest in pushing this forward?

[tjd2002]

This repo seems to be quite soundly dead but there's an actively-developed fork at : https://github.com/fcollonval/jupyter_conda (Thanks @fcollonval)