Feat: Ability to run Engine with default config

Dockerfile

@@ -17,6 +17,7 @@ RUN mkdir -p /srv/tests
 RUN mkdir -p /srv/config
 COPY src /srv/src
 COPY tests /srv/tests
+COPY config/sample.engine-core.docker.ini /srv/config/engine-core.ini
 COPY Makefile /srv/Makefile
 COPY VERSION /srv/VERSION
 VOLUME ["/srv/socket", "/srv/logs", "/srv/audio/source", "/srv/audio/playlist", "/srv/audio/fallback"]