Clean up Dockerfile

docker/Dockerfile

 FROM debian:buster-slim
 
+LABEL maintainer="Cecylia Bocovich <cohosh@torproject.org>"
+
 #install python
 RUN apt-get update && apt-get install -y git wget tcpdump \
-    python3 python3-stem tor obfs4proxy
+    python3 python3-stem tor obfs4proxy && apt-get clean
 
 #install Go
 RUN wget https://golang.org/dl/go1.15.14.linux-amd64.tar.gz && \
@@ -12,7 +14,8 @@ ENV PATH=$PATH:/usr/local/go/bin
 
 #install snowflake
 RUN git clone https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git \
-    && cd snowflake/client && go get -d && go build && cp client /usr/bin/snowflake
+    && cd snowflake/client && go get -d && go build && mv client /usr/bin/snowflake \
+    && cd - && rm -rf snowflake
 
 RUN git clone https://github.com/cohosh/bridgetest.git && \
     cd bridgetest/stun-test && go get -d && go build