[Etherpad] Remove --chown flag (not available before Docker 17.09)

pica-etherpad/Dockerfile

@@ -57,7 +57,8 @@ COPY entrypoint.sh /opt/etherpad-lite/entrypoint.sh
 RUN useradd --uid ${UID} --create-home etherpad
 
 # Import des fichiers téléchargés dans l'image downloader
-COPY --from=downloader --chown=etherpad /opt/etherpad-lite /opt/etherpad-lite/
+COPY --from=downloader /opt/etherpad-lite /opt/etherpad-lite/
+RUN chown -R etherpad /opt/etherpad-lite
 
 RUN apt-get update && \
     apt-get install -y curl nano postgresql-client && \

pica-etherpad/docker-compose.yml

@@ -70,6 +70,7 @@ services:
   etherpad-week-app:
     image: registry.picasoft.net/pica-etherpad:1.8.4
     container_name: etherpad-week-app
+    build: .
     depends_on:
       - etherpad-week-db
     security_opt: