Enable go module support for go environment (#1152)

examples/go/module-example/main.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"net/http"
+
+	"github.com/golang/example/stringutil"
+)
+
+// Handler is the entry point for this fission function
+func Handler(w http.ResponseWriter, r *http.Request) {
+	msg := stringutil.Reverse(stringutil.Reverse("Vendor Example Test"))
+	w.Write([]byte(msg))
+}