Add Dockerfile build

Dockerfile

+FROM golang:1.4.1
+RUN mkdir /kube-bench
+WORKDIR /kube-bench
+RUN wget https://raw.githubusercontent.com/aquasecurity/kubernetes-bench-security/master/cfg/config.yaml && \
+    wget https://raw.githubusercontent.com/aquasecurity/kubernetes-bench-security/master/cfg/federated.yaml && \
+    wget https://raw.githubusercontent.com/aquasecurity/kubernetes-bench-security/master/cfg/master.yaml && \
+    wget https://raw.githubusercontent.com/aquasecurity/kubernetes-bench-security/master/cfg/node.yaml
+RUN go get github.com/aquasecurity/kubernetes-bench-security
+RUN cp /go/bin/kubernetes-bench-security /kube-bench/ && chmod +x /kube-bench/kubernetes-bench-security
+
+FROM alpine:latest
+RUN mkdir -p /kube-bench/cfg
+COPY --from=0 /kube-bench/kubernetes-bench-security /kube-bench/kube-bench
+COPY --from=0 /kube-bench/config.yaml /kube-bench/cfg/config.yaml
+COPY --from=0 /kube-bench/federated.yaml /kube-bench/cfg/federated.yaml
+COPY --from=0 /kube-bench/master.yaml /kube-bench/cfg/master.yaml
+COPY --from=0 /kube-bench/node.yaml /kube-bench/cfg/node.yaml
+ADD entrypoint.sh /entrypoint.sh
+ENTRYPOINT /entrypoint.sh

entrypoint.sh

+#!/bin/sh
+if [ -d /host ]; then
+  mkdir -p /host/cfg/
+  yes | cp -rf ./kube-bench/cfg/* /host/cfg/
+  yes | cp -rf ./kube-bench/kube-bench /host/
+  echo "=== You can now run ./kube-bench from your host ==="
+else
+  echo "Error: please mount a host directory as /host volume"
+  echo "docker run --rm -v `pwd`:/host aquasec/kube-bench"
+  exit 
+fi