Navigate without second parameter

[niboc]

Hi Tanner, many times I just want to navigate to specific route, but there're no need for passing a secondr parameter.

I added a default value to _ref2 on the index.es.js file on function navigate, but I think it's not a "tanner way", so if you can fix it, I'll appreciate it.

Here is my temporary fix
_ref2 = _ref2 || {};

Thanks for this awesome router