Running tests also builds Xli
Make Uri::Encode confirm to spec.

Spec: http://en.wikipedia.org/wiki/Percent-encoding#Types_of_URI_characters

Add unit test for Uri::Encode
AutoEncodeUri encodes everything except %

This is needed to make http automatically encode uris in the same way as
JavaScript.
Automatically encode urls

To make Xli HTTP behave like JS and .net backends