Launch mybinder in README throws error

[lmarini]

ERROR: Cannot install -r requirements.txt (line 11), -r requirements.txt (line 18) and prompt-toolkit==1.0.15 because these package versions have conflicting dependencies.

The conflict is caused by:
    The user requested prompt-toolkit==1.0.15
    ipython 5.0.0 depends on prompt-toolkit<2.0.0 and >=1.0.3
    jupyter-console 6.0.0 depends on prompt-toolkit<2.1.0 and >=2.0.0

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/user_guide/#fixing-conflicting-dependencies