'If the \'now\' argument is true then starts using encryption immidiatedly.
If \'now\' in false then starts encryption as soon as TLS feature is
declared by the server (if it were already declared - it is ok).'

def PlugIn(self, owner, now=0):

    if owner.__dict__.has_key('TLS'):
        return
    PlugIn.PlugIn(self, owner)
    DBG_LINE = 'TLS'
    if now:
        return self._startSSL()
    if self._owner.Dispatcher.Stream.features:
        try:
            self.FeaturesHandler(self._owner.Dispatcher, self._owner.Dispatcher.Stream.features)
        except NodeProcessed:
            pass
    else:
        self._owner.RegisterHandlerOnce('features', self.FeaturesHandler, xmlns=NS_STREAMS)
    self.starttls = None
