add vendoring with go dep

vendor/github.com/influxdata/influxdb/releng/unit-tests/Dockerfile

@@ -0,0 +1,15 @@
+ARG GO_VERSION
+FROM golang:${GO_VERSION}-alpine
+
+RUN apk add --no-cache \
+      bash \
+      jq \
+      git
+
+RUN go get -u github.com/jstemmer/go-junit-report && \
+      mv /go/bin/go-junit-report /usr/bin/go-junit-report && \
+      rm -rf /go/*
+
+COPY fs/ /
+
+ENTRYPOINT ["influxdb_prebuild_tests.bash"]