PLT-6518 Fixed user's locale not being loaded with redux actions (#6359)

* Stopped ManageLanguages component from mutating user

* Removed obsolete reference to mm_user

* PLT-6518 Fixed user's locale not being loaded with redux actions

webapp/components/login/login_controller.jsx

@@ -210,7 +210,7 @@ export default class LoginController extends React.Component {
 
     finishSignin(team) {
         const query = this.props.location.query;
-        GlobalActions.loadDefaultLocale();
+        GlobalActions.loadCurrentLocale();
         if (query.redirect_to) {
             browserHistory.push(query.redirect_to);
         } else if (team) {

webapp/components/root.jsx

@@ -20,8 +20,8 @@ export default class Root extends React.Component {
     constructor(props) {
         super(props);
         this.state = {
-            locale: 'en',
-            translations: null
+            locale: LocalizationStore.getLocale(),
+            translations: LocalizationStore.getTranslations()
         };
 
         this.localizationChanged = this.localizationChanged.bind(this);
@@ -113,7 +113,7 @@ export default class Root extends React.Component {
         LocalizationStore.addChangeListener(this.localizationChanged);
 
         // Get our localizaiton
-        GlobalActions.loadDefaultLocale();
+        GlobalActions.loadCurrentLocale();
     }
 
     componentWillUnmount() {

webapp/components/user_settings/manage_languages.jsx

@@ -33,12 +33,10 @@ export default class ManageLanguage extends React.Component {
     changeLanguage(e) {
         e.preventDefault();
 
-        var user = this.props.user;
-        var locale = this.state.locale;
-
-        user.locale = locale;
-
-        this.submitUser(user);
+        this.submitUser({
+            ...this.props.user,
+            locale: this.state.locale
+        });
     }
     submitUser(user) {
         updateUser(user, Constants.UserUpdateEvents.LANGUAGE,