PicView applied wrong language setting.

[a224515a]

Describe the bug
I changed the language to English, however, PicView was still displayed in simplified Chinese.
(it is probably because my system setting is traditional Chinese)

To Reproduce
Steps to reproduce the behavior:

1. Go to Settings window
2. Click on 'Language'
3. Scroll down to 'English'
4. Restart PicView
5. NOTHING HAPPENS

Expected behavior
PicView should be displayed in English.

Additional context
I've issued a pull request (#13 ) to add traditional Chinese translation.