Enhancement/various filetypes

[r1d3th3wav3s]

• Improved logging
• Adds detection of various file types
• Improved detection of UTF-8 / ASCII files
• Adds a unit test for UTF-8 files

[psrok1]

It would be nice if you also provide test files for added extensions: see https://github.com/CERT-Polska/karton-classifier/tree/master/tests/testdata

PS.: I've fixed few simple errors and linting + merged it with upstream changes, so please make a pull before applying yours.

[r1d3th3wav3s]

updated my pull request (removed some too specific detections, added unit-tests9

[nazywam]

LGTM
One small note - I think we should stick to - instead of _ in the "kind" fields. There isn't an official guide per se but looking at other filetypes we've used only - so far