exclude vendor from 'go vet'

circle.yml

@@ -37,7 +37,7 @@ test:
     - go version
     - echo " ! gofmt -d main.go       2>&1 | read " | bash
     - echo " ! gofmt -d exporter/*.go 2>&1 | read " | bash
-    - go vet ./...
+    - go vet $(go list ./... | grep -v /vendor/) 
     - go get github.com/mattn/goveralls
     - go get golang.org/x/tools/cmd/cover
   override: