Given an app, run detect script on it to determine whether it can be
        built with this pack.  Return True/False.

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