Topaz doesn't mount a volume for decision logs

[ronenh]

Topaz can write decision logs to a local file using the type: file option in the decision_logger config section.
However, when using topaz start to run the container, that path isn't mounted from the local filesystem.
As a result, decision logs are written to a file inside the container but aren't visible in the host filesystem.

When file logging is enabled, topaz start should mount the path specified in decision_logger.config.log_file_path.

For example, with this config:

decision_logger:
  type: file
  config:
    log_file_path: "${TOPAZ_DIR}/decision_logs"
    max_file_size_mb: 20
    max_file_count: 3

${TOPAZ_DIR}/decision_logs should be mounted as a volume in the topaz container.

[carabasdaniel]

Fixed by #234