please add requirements.txt to be compatible with mybinder.org

[Tony]

Hello! This is quite an interesting project.

I noticed you added the dependencie son the README.md file.
Would you mind adding them on a requirements.txt file?

With this it would then be possible to send the mybinder URL from your repo to friends such that they can try it out without having a python environment with tensorflow on their local machine:
https://mybinder.org/v2/gh/greydanus/scribe/master?filepath=sample.ipynb
At the moment without requirements.txt file the mybinder does not include numpy etc in the build.

Thanks for considering it!