ConfigTool: General Widget update

Fix #539

Tasks:
- [x] Update General widget look to match mock-up
- [x] Implement "Help us translate" button functionality
- [x] Implement "Reset to defaults" button functionality
- [x] Implement "Clear talks" button functionality (Removed after feedback)
- [x] Add confirmation dialog to both(?) reset buttons
- [x] Add translation code for new labels
@mtomwing should this videodir variable be renamed to video_dir? The reason I'm unsure is that it sort of mirrors the videodir variable in the config profile class referenced below with "self.config.videodir".