Revert changes in AppVeyor conf
Revert changes in AppVeyor conf

No SciPy wheels on Windows in the short term, see
https://github.com/scipy/scipy/issues/5461

Keep using conda for conflicting packages, namely
NumPy, SciPy and numba.

anhiga/poliastro,anhiga/poliastro,anhiga/poliastro,newlawrence/poliastro,poliastro/poliastro,Juanlu001/poliastro,Juanlu001/poliastro,newlawrence/poliastro,newlawrence/poliastro,Juanlu001/poliastro