Instead of re-inventing the wheel regarding configuration location
handling and validation, this introduces a new command flag `--config`
allowing for full flexibility of configuration filename and location.
This flag can also be defined via environment variable which allows
an easy way of starting the bot from command line, inside a Docker
container or using the Helm Chart.
It makes the custom environment lookup unnecessary and reduces some
complexity during startup and for writing tests.
Resolves: #10
Signed-off-by: Steven Kriegler <sk.bunsenbrenner@gmail.com>
dc3969cd05