Install yapf and flake8 required by build-tools lint

backend/Dockerfile

@@ -1,10 +1,10 @@
 FROM ubuntu:yakkety
 ENV GOPATH /go
 ENV GOVERSION 1.7
-ENV PATH /go/bin:/usr/lib/go-${GOVERSION}/bin:/usr/bin:/bin:/usr/sbin:/sbin
+ENV PATH /go/bin:/usr/lib/go-${GOVERSION}/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin
 ENV SCOPE_SKIP_UI_ASSETS true
 RUN apt-get update && \
-	apt-get install -y libpcap-dev python-requests time file shellcheck golang-${GOVERSION} git gcc-arm-linux-gnueabihf curl && \
+	apt-get install -y libpcap-dev python-requests time file shellcheck golang-${GOVERSION} git gcc-arm-linux-gnueabihf curl python-pip && \
 	rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 RUN go clean -i net && \
 	go install -tags netgo std && \
@@ -21,5 +21,6 @@ RUN go get -tags netgo \
 		github.com/client9/misspell/cmd/misspell && \
 	chmod a+wr --recursive /usr/lib/go-${GOVERSION}/pkg && \
 	rm -rf /go/pkg/ /go/src/
+RUN pip install yapf==0.16.2 flake8==3.3.0
 COPY build.sh /
 ENTRYPOINT ["/build.sh"]