Help needed: vendor files for Prometheus support

These are the vendor files needed for Prometheus support.
I have not been able to figure out how to do this properly with gopkg.

vendor/github.com/golang/protobuf/.travis.yml

@@ -0,0 +1,18 @@
+sudo: false
+language: go
+go:
+- 1.6.x
+- 1.7.x
+- 1.8.x
+- 1.9.x
+
+install:
+  - go get -v -d -t github.com/golang/protobuf/...
+  - curl -L https://github.com/google/protobuf/releases/download/v3.3.0/protoc-3.3.0-linux-x86_64.zip -o /tmp/protoc.zip
+  - unzip /tmp/protoc.zip -d $HOME/protoc
+
+env:
+  - PATH=$HOME/protoc/bin:$PATH
+
+script:
+  - make all test