Switch to uritemplate-test

I wanted to use uri-template, but before I do I'd like it to pass all uritemplate-test, made of
- official tests included in the RFC
- semi-official tests written by Mark Nottingham

Current status:
Failed 39 (26 PEG) out of 227 tests

* 26 PEG - the PEG parser failed to parse the URI template; the rest of the failures is that the library expanded into a different URI