Code review comment for lp:~dylanmccall/ubiquity/lp-476269

Part of my fix, where I had Ubiquity itself select the ideal fallback locale for the slideshow, was very flawed. This new version removes that excess functionality, where Javascript in the slideshow now handles all the necessary thinking in a manner consistent with other applications.

In this new version I have completely removed slideshow_get_available_locale() from ubiquity/frontend/base.py, kde_ui.py and gtk_ui.py. The slideshow is simply handed the entire current locale name, such as en_CA.UTF8, and it handles the rest.