add docker and publish the current version to hub

Closes #10

.dockerignore

@@ -0,0 +1,4 @@
+/target
+
+.env*
+!.envrc

Dockerfile

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+FROM rust:1.62.0-slim-buster
+
+WORKDIR /app
+
+COPY Cargo.* ./
+COPY ./src ./src
+
+RUN cargo install --bin vnetod --path . \
+  && rm -rf ./src Cargo.*
+
+VOLUME ["/data"]
+
+WORKDIR /data
+
+ENTRYPOINT ["/usr/local/cargo/bin/vnetod"]
+