Fix #614 Add video scaling options

Freeseer now supports converting video signals from one display
resolution to another. Technically we already supported this, but there
were no scaling options so it wasn't very useful.

The following scaling options are now available when recording video:

- No scaling
- 240p (320x240)
- 360p (480x360)
- 480p (640x480)
- 720p (1280x720)
- 1080p (1920x1080)
Fix #476 Auto language changing when first launch

- Freeseer will now scan the System language for the first time.
If there is translation for the location, the interface language
will be set to that language by default. Otherwise en_US will be used.
- Unit test for this function is also added..