Adding general input groups and adding Mac support

This release generalizes the libraries interface away from the original Premise usecase (correct classification vs. misclassification) to the more general idea that Premise compares two groups of texts.

It also now automatically checks which binary version of Premise works on your system, thus enabling direct additional Mac support.

Release version is identical with the version of pip.

Full Changelog: v0.1.1...v.0.2.0