Upgrade bazel version to 0.19 for docker build

Change-Id: I8d86a4db66297a1684c4faa35a535013c99ea3c2
diff --git a/Dockerfile b/Dockerfile
index c83b2fb..e62252f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,7 +17,7 @@
 # build problems
 WORKDIR /src/onos
 RUN apt-get update && apt-get install -y zip python git bzip2 build-essential && \
-        curl -L -o bazel.sh https://github.com/bazelbuild/bazel/releases/download/0.17.1/bazel-0.17.1-installer-linux-x86_64.sh && \
+        curl -L -o bazel.sh https://github.com/bazelbuild/bazel/releases/download/0.19.0/bazel-0.19.0-installer-linux-x86_64.sh && \
         chmod +x bazel.sh && \
         ./bazel.sh --user && \
         export ONOS_ROOT=/src/onos && \