Move bazel build tarball test to prow

CORS-751

.travis.yml

@@ -27,5 +27,5 @@ jobs:
     - script: "docker run -v $PWD:$PWD -w $PWD quay.io/coreos/golang-testing golint -set_exit_status installer/..."
       name: Go lint
     - stage: Build
-      script: "chmod 0777 $PWD && docker run -v $PWD:$PWD:rw -w $PWD $BAZEL_IMG bazel build tarball"
+      script: ./hack/test-bazel-build-tarball.sh
       name: Build tarball

hack/test-bazel-build-tarball.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+if [ "$IS_CONTAINER" != "" ]; then
+  set -x
+  bazel --output_base=/tmp build tarball
+else
+  docker run -e IS_CONTAINER='TRUE' --rm -v "$PWD":"$PWD" -v /tmp:/tmp:rw -w "$PWD" quay.io/coreos/tectonic-builder:bazel-v0.3 ./hack/test-bazel-build-tarball.sh
+fi