allow fully qualified paths in rest definitions

[heapwolf]

when defining a REST call, it may be desired to override the default host (either implied or as defined in the using method). In there case where the URL provided is "fully qualified", the host, port and protocol etc should not be prepended.

    var porter = Porter({

      users: {
        list: ['get', 'http://api.twitter.com/v1/feeds/timeline/:id'],
        update: ['post', '/api/apps/:username']
      }

    });