mybinder fails to install ktnumpy 0.1.4

When trying to execute Kotlin notebook at mybinder I'm getting an error:
```
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output." when executing the command: python -m pip install -i https://pypi.org/simple/ ktnumpy==0.1.4
```

The notebook: https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/contours.ipynb

Start with the contours.ipynb notebook linked in the report and reproduce the `pip install ktnumpy==0.1.4` command on mybinder. Inspect the reported `python setup.py egg_info` failure and its logs; done means the package installs successfully and the notebook can execute there.

Written by the indexing model from the issue text.