Remove misleading text about Router from README.

I was checking out Exoskeleton when I came upon this surprising line in the README:

> Router with query string support

Digging through the source, I saw that this library doesn't actually parse the query string, which is how I think most folks would interpret this. I dug through the issues and found #82, where @akre54 explains:

> This refers to the fact that at the time Exoskeleton came out, Backbone didn't yet handle urls with querystrings

Keeping this line in the README is a bit misleading, I think. Sure, it made sense back in the day, but now what you're really saying is

> Router that supports query strings in the same way that Backbone does

which is already explained in the README where it states that this library passes Backbone's tests.