Fixed implementation of REST_REQUEST_AGENT_HANDLER to avoid wrong path in inherited routine.
Allow to build a URI_TEMPLATE from another URI TEMPLATE,
this way, if later we have more attribute (status or settings) to URI_TEMPLATE,
we'll be able to change the `template' without breaking the settings
as specified by http://tools.ietf.org/html/draft-gregorio-uritemplate-05
(it seems to contains some error in the spec .. or minor incoherences, to double check)
The matcher is basic, it does not handle all the details of the string builder, but that seems ok for now.