refactor: Minor code and UI improvements

Sources/Earthquake Network/Controllers/EQNBaseViewController.m

@@ -17,6 +17,13 @@
 
 @implementation EQNBaseViewController
 
+#pragma mark - Accessories
+
+- (BOOL)isBannerVisible
+{
+    return ![EQNPurchaseUtility isProVersionEnabled];
+}
+
 #pragma mark - View Lifecycle
 
 - (void)viewDidLoad
@@ -52,7 +59,7 @@
 - (void)handleAdBanner
 {
     // ad banner mut be displayed only for non pro users
-    if ([EQNPurchaseUtility isProVersionEnabled]) {
+    if (!self.isBannerVisible) {
         [self hideAdBanner];
         return;
     }