Fix GCS

Signed-off-by: Olivier Gambier <olivier@docker.com>

vendor/google.golang.org/grpc/.travis.yml

@@ -1,4 +1,13 @@
 language: go
 
+before_install:
+  - go get github.com/axw/gocov/gocov
+  - go get github.com/mattn/goveralls
+  - go get golang.org/x/tools/cmd/cover
+
+install:
+  - mkdir -p "$GOPATH/src/google.golang.org"
+  - mv "$TRAVIS_BUILD_DIR" "$GOPATH/src/google.golang.org/grpc"
+
 script:
   - make test testrace