PLT-1800 Load server side locale from the config.json (#3092)

* PLT-1800 Load server side locale from the config.json

* Add support for locales with country specifics

* Fix localization on served locale file as plain/text

store/sql_store_test.go

@@ -16,7 +16,7 @@ var store Store
 func Setup() {
 	if store == nil {
 		utils.LoadConfig("config.json")
-		utils.InitTranslations()
+		utils.InitTranslations(utils.Cfg.LocalizationSettings)
 		store = NewSqlStore()
 
 		store.MarkSystemRanUnitTests()