resolves #200

Update python dependencies using poetry.

Load the SECRET_KEY from the config.yml file or by environment variable.
This allows us to run collectstatic without a special config.yml file or a specific
static.py settings file.

The application is small and for internal use so we can deliver
static assets directly by the application.

The wait-for-mysql.sh is good for development proposes,
so I've readd it. I've also included it to the docker image,
just in case.
The run Makefile target run the DBs inside docker.