use text ellipsis

This replaces text overflow by ellipsis for buttons and in the settings menu. Text overflow may occur when an element has dynamic content (e.g. a translated string) and a maximum width.

This is only a minimal change. Still I would like to get feedback. I think this is an improvement because text overflow looks broken and therefore should be avoided. Still replacing text overflow by ellipsis removes information. So I am not sure if this is the bast way to do it.

![ellipsis_after1](https://f.cloud.github.com/assets/202576/1796101/64cd641c-6a53-11e3-9127-e32dc3a9c19a.png)