First steps: fix page control background color

Sources/VLCFirstStepsViewController.m

@@ -43,6 +43,7 @@
     UIBarButtonItem *dismissButton = [UIBarButtonItem themedDoneButtonWithTarget:self andSelector:@selector(dismissFirstSteps)];
     self.navigationItem.rightBarButtonItem = dismissButton;
     self.title = NSLocalizedString(@"FIRST_STEPS_WELCOME", @"");
+    self.view.backgroundColor = [UIColor blackColor];
 
     [self addChildViewController:pageVC];
     [self.view addSubview:[pageVC view]];