Merge PR from @chrros95

Several Changes:
- Uwsgi now listens on two sockets 8080 for http protocol and 8000 for uwsgi protocol
- Add a read_timeout in documentation for Nginx configuration 
- Expose 8024 properly in Core image
- Expose 8080 and 8000 both in Web image
- Rearange the commands to get even less number of layers.
- Add SIGINT as stop signal in web because uwsgi needs it shut down gracefully
- Enable threads in default uwsgi configuration

Fix #64, Fix #15

core/Dockerfile

@@ -2,25 +2,25 @@ FROM python:3.6-alpine
 
 MAINTAINER Abhilash Raj
 
-# Install the latest master branch of the mailman directly
-# from the Gitlab.
+#Add startup script to container
+ADD assets/run.sh /opt/run.sh
+
+#Install all required packages, add user for executing mailman and set execution rights for startup script
 RUN apk update \
     && apk add --virtual build-deps gcc python3-dev musl-dev \
     && apk add postgresql-dev bash su-exec postgresql-client \
     && pip install psycopg2 mailman==3.1.0 mailman-hyperkitty==1.1.0 \
-    && apk del build-deps
-
-ADD assets/run.sh /opt/run.sh
+    && apk del build-deps \
+    && adduser -S mailman \
+    && chmod a+x /opt/run.sh
 
 # Change the working directory.
 WORKDIR /opt/mailman
 
-EXPOSE 8001
-
-ENTRYPOINT ["/opt/run.sh"]
+#Expose the ports for the api (8001) and lmtp (8024)
+EXPOSE 8001 8024
 
 ENV MAILMAN_CONFIG_FILE /etc/mailman.cfg
 
-RUN adduser -S mailman
-
-CMD ["/usr/local/bin/master"]
+ENTRYPOINT ["/opt/run.sh"]
+CMD ["/usr/local/bin/master"]