Refactor locale handling

[chrisgarrity]

Bring gui in line with this discussion:
#3431 (comment)

With the addition of the LocalizationHOC, it should be handling the redux updates.

The language switcher should be using the onSetLocale passed in by whatever is using GUI. The onSetLocale should end up changing the locale that is passed as a prop to GUI. When the locale prop switches, the LocalizationHOC can handle dispatching the locale change.