Fixed #614 Change resolution for input Video

Fixes #614
- Add more options for Video Passthrough Setting, which will change the output video resolution.

![default](https://cloud.githubusercontent.com/assets/5828044/4518433/e098dd04-4c8b-11e4-9422-781c8695115e.png)


You mean replace the 'StringOption' to 'ChoiceOption'?