code: def detect(self, app):
          
          script = os.path.join(self.folder, 'bin', 'detect')
          cmd = '%s %s' % (script, app.folder)
          result = run(cmd)
          return result.status_code == 0
docs: Given an app, run detect script on it to determine whether it can be
          built with this pack.  Return True/False.