Dftbplus-step

* Logging at the INFO level made the output from geomTRIC too verbose. Changed to
DEBUG level.

* The code had several errors to do with detecting whether the calculation was
spin-polarized or not. This has been fixed and the detection simplified.

* Added the standard results -- energy, gradients, and model -- that can be written
to Results.json for drivers like Structure Step and Thermochemistry Step.

* The initial version of dftbplus.ini was not generated correctly if it was
missing. This caused a crash when running DFTB+.