Use vendor when building (#201)

* Use vendor code for all go calls

* Add missing vendor dependencies

* Add travis_retry to yarn install

* Fix go test call

vendor/github.com/99designs/gqlgen/codegen/complexity.go

@@ -0,0 +1,11 @@
+package codegen
+
+func (o *Object) UniqueFields() map[string][]*Field {
+	m := map[string][]*Field{}
+
+	for _, f := range o.Fields {
+		m[f.GoFieldName] = append(m[f.GoFieldName], f)
+	}
+
+	return m
+}