Force usage of OS default language for UI

Fallback.  Better than just assuming english!
Add os default language to palisades.i18n

Fetching the default language from the OS via the locale module.
Trying to be aware of distribution config

A distribution of a UI might have preferences located in a file in a
known location.  If this is the case, we want to fetch those
preferences.  If no known files can be found, we want to instead make
reasonable assumptions about default values.
Fixing import and runtime errors.
Updating elements_test:ApplicationTest

Accessing timber configuration from a common object attribute and
adding a test case for the palisades.launch() method.
Adding a function to extract language codes