Locales cached in PrefManager and AssetCacheManager are not reconstructed properly

[GSala]

In the PrefManager (L45) and AssetCacheManager (L25) , Locales are constructed using the single parameter constructor which expects ISO 639 language codes.
The keys used in both of these managers are language tags that combine a language code and a country code.
They should probably use Locale.forLanguageTag()