message: Fix error when mediaUrl is undefined
diff: @@ -54,10 +54,13 @@ function TwilioSMS(configuration) {
  var sms = {
  body: message.text,
  from: configuration.twilio_number,
  - to: message.channel,
  - mediaUrl: message.mediaUrl
  + to: message.channel
  };
  + if (message.hasOwnProperty('medaUrl')) {
  + sms.mediaUrl = message.mediaUrl
  + }
  +
  client.messages.create(sms, function(err, message) {
  if (err) {
  