Pandas and scikit-learn are handy to have for data processing which we
are going to do more and more in ERP5 context. Matplotlib is very handy
to have when one works with Jupyter, but also can be used by just
backend code to generate graphs.

From this point of view it makes sense to have this eggs always
available out of the box. To do so move them from Wendelin to ERP5.

/suggested-by @tiwariayush
/reviewed-by @Tyagov (on nexedi/slapos!43)