Add locale getter for Player

Adds a getLocale method to the player interface. 

NMS keeps track of which locale the player has selected in EntityPlayer field 'locale' as a String (default "en_US") and updates it when packet 0x15 Client Settings is sent (on connect + when settings are changed). 

Will need to store the parsed Locale and update on packet to avoid having to lookup with LocaleUtils on each potential call