feedbackview with comma in sender-Attribute

@maethu Reply to a received Email over the Addressblock-Feedbackview fails if the Visitor entered a Name with a comma.

![bildschirmfoto 2014-04-15 um 13 42 19](https://cloud.githubusercontent.com/assets/557005/2706538/17c7f0de-c493-11e3-9a49-3a2b3f74c9dc.png)

![bildschirmfoto 2014-04-15 um 13 42 30](https://cloud.githubusercontent.com/assets/557005/2706537/17c7a070-c493-11e3-9868-53e9858865d4.png)

![bildschirmfoto 2014-04-15 um 13 42 37](https://cloud.githubusercontent.com/assets/557005/2706539/17c9d516-c493-11e3-9452-129506ccd890.png)