Fix String#toQueryParams to support params with query params.

With the current implementation of toQueryParams, if you have a URL like http://site.com?param1=http://site2.com?site2param1=value, it will parse the string incorrectly. In that case, you would expect an object containing param1: http://site2.com?site2param1=value.

I've made the non-Fuse fix here: https://gist.github.com/8ceba659dcd096be2abc

Notice how we split on the ?, but rejoin the string for everything after the first ? in the string.

I also remove the hashes per pair instead of globally, since there could be a hash in the query param URL like http://site.com?param1=http://site2.com?site2param1=value#site2hash&param2=value2#hash.

Yes, I understand that the URL's in the params should be URL encoded, but I've seen a lot of implementations when they are not.