feat: Removed supervisor and rsyslog

As mentioned in discussion #54, since version 3.3.0, postfix can run in
foreground mode, and since 3.4.0 it can log directly to stdout.

Dockerfile

@@ -4,12 +4,11 @@ MAINTAINER Juan Luis Baptiste juan.baptiste@gmail.com
 
 RUN apk update && \
     apk add bash gawk cyrus-sasl cyrus-sasl-login cyrus-sasl-crammd5 mailx \
-    perl supervisor postfix rsyslog && \
+    postfix && \
     rm -rf /var/cache/apk/* && \
     mkdir -p /var/log/supervisor/ /var/run/supervisor/ && \
     sed -i -e 's/inet_interfaces = localhost/inet_interfaces = all/g' /etc/postfix/main.cf
 
-COPY etc/ /etc/
 COPY run.sh /
 RUN chmod +x /run.sh
 RUN newaliases