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)


We have a resmap that should be reworked for this [1]. This kind of setting shouldn't be done in the GUI components because we'd need to be able to use it for CLI Frontends (or any other type of frontend) too. So it should be designed in some backend place that a frontend could take advantage of.

[1] https://github.com/Freeseer/freeseer/blob/master/src/freeseer/settings.py#L42