Fix missing python dependency and add some conveniences to weechat (#498)

* Switch user from a system user to a regular user

* Add a run string

* Add python dependency for weechat-python.

weechat/Dockerfile

@@ -1,13 +1,24 @@
+# Run weechat in a container
+#
+# docker run -it \
+#	-v $HOME/.weechat/home/user/.weechat \
+#	--name weechat \
+#	jess/weechat
+#
+
 FROM alpine:latest
 
 RUN apk add --no-cache \
 	weechat \
 	weechat-perl \
-	weechat-python
+	weechat-python \
+	python
 
+ARG RUNTIME_UID
+ENV RUNTIME_UID ${UID:-1000}
 ENV HOME /home/user
 
-RUN adduser -S user \
+RUN adduser -D user -u ${RUNTIME_UID} \
 	&& chown -R user $HOME
 
 WORKDIR $HOME