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/cmd/version.go

@@ -0,0 +1,16 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/99designs/gqlgen/graphql"
+	"github.com/urfave/cli"
+)
+
+var versionCmd = cli.Command{
+	Name:  "version",
+	Usage: "print the version string",
+	Action: func(ctx *cli.Context) {
+		fmt.Println(graphql.Version)
+	},
+}