readme example is not working

[shutcode]

expected result: resp including a vertice id
but the real result: [SERVER SERIALIZATION ERROR]

// replace map[string]string{"x": "1234"} with this:
map[string]string{"x": "'1234'"},
// but got 
// [<nil>]

[cyrilzh]

gremgo simply set the binding and rebinding data to the Args of the request to gremlin server.

	req.Args["bindings"] = bindings
	req.Args["rebindings"] = rebindings

It works on my side with Azure Cosmos DB.