Allow linking to myapp.com/root/ when using root

I could be wrong, no tests except within my app, but it seems like setting a root option for the Router, like `root: "/admin/"`, then linking to `href="/admin/"` within the app, redirects to localhost/admin instead of localhost/admin/. I'm not sure if both of these checks are necessary (could even just do "url isnt root" instead of the current "url isnt '/'") but I wasn't sure if that would cause any chaos for other situations-
Merge pull request #796 from davidkaneda/patch-1

Allow linking to myapp.com/root/ when using root