feat(dockerfile): add jwt command line utility (#82)

Author: ultimateboy

rootfs/Dockerfile

@@ -59,6 +59,7 @@ RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
   github.com/golang/dep/cmd/dep \
   github.com/haya14busa/goverage \
   github.com/constabulary/gb/... \
+  github.com/dgrijalva/jwt-go/cmd/jwt \
   && gometalinter --install \
   && pip install --disable-pip-version-check --no-cache-dir azure-cli==${AZCLI_VERSION} \
   && apt-get purge --auto-remove -y libffi-dev python-dev python-pip