Fhem

- fix bug that prevented multiple concurrent connections with authentication
- drop Python 2 support
- modernized python package

* Fixes 17, 14.
* TavisCI self-test framework.
* Published on [PyPi](https://pypi.org/project/fhem/)

- New get() api. see [doc](https://domschl.github.io/python-fhem/doc/_build/html/index.html)
- Small fix for sync telnet transactions.