Convert RFC 1738 plus encoding to RFC 3986 percent encoding

Hi Mario,

Thanks for creating your URL normalising module. I like that it sorts the query parameter names into a consistent (alphabetic) order - you've saved me the job of having to create something similar.

I've added support for converting deprecated RFC 1738 style plus encoding of spaces in URLs to use RFC 3986 style percent encoding instead - hope you consider it worthy of inclusion.

Cheers,
Lovell