Duplicated _config information

[sjunges]

We have some duplicated info in https://github.com/moves-rwth/stormpy/blob/master/cmake/config.py.in and https://github.com/moves-rwth/stormpy/blob/master/cmake/info_config.py.in. I wonder which to keep.

[volkm]

I think the first one is not needed anymore after the CMake update in #217