Enable Dark theme

TODO:
- fix the app freeze when user changes the app theme.

Riot/ViewController/SegmentedViewController.m

@@ -172,6 +172,14 @@
 - (void)userInterfaceThemeDidChange
 {
     self.defaultBarTintColor = kRiotSecondaryBgColor;
+    self.barTitleColor = kRiotPrimaryTextColor;
+    
+    self.view.backgroundColor = kRiotPrimaryBgColor;
+}
+
+- (UIStatusBarStyle)preferredStatusBarStyle
+{
+    return kRiotDesignStatusBarStyle;
 }
 
 - (void)viewWillAppear:(BOOL)animated