[SEBA-314] Refactoring multistructlog

- Redid the way loggers are created to use vanilla structlog
  - This fixes the incorrect line numbering and similar in SEBA-314
- Fix/rewrite unit tests
- Apply pep8 formatting
- Make compatible with Python 3.x, enable multi-version testing with tox
- Removed XOS specific code

Change-Id: I615bc6f32ba2592475e3a8cf22850c563001a3d4
11 files changed