fix Dockerfile.develop

DOCKER/Dockerfile.develop

@@ -18,6 +18,7 @@ RUN mkdir -p /go/src/github.com/tendermint/tendermint && \
     cd /go/src/github.com/tendermint/tendermint && \
     git clone https://github.com/tendermint/tendermint . && \
     git checkout develop && \
+    make get_tools && \
     make get_vendor_deps && \
     make install && \
     cd - && \