Store server config in yml file

Allow to specify a yml file containing the server description.

As result the server config should be more readable.

If it's fine for you, i would like in the future to remove from the resources everything which is about the web server, for sure the ssl keys description, optionally the private tokens, optionally the sql access. This could simplify a bit our resource connector.

# Daiquiri server

port: 8080

static_folder: "./daiquiri-ui.git/build/"

resource_folders:
   - "./beamline_configuration/daiquiri"
   - "./daiquiri_private"

This configuration file is optional, and can be overwritten by the command line arguments