Support GA services

Support screen tracking via Google Analytics.

#335

Vector/ViewController/DirectoryViewController.m

@@ -50,10 +50,17 @@
     self.tableView.tableFooterView = [[UIView alloc] init];
 }
 
-
 - (void)viewWillAppear:(BOOL)animated
 {
     [super viewWillAppear:animated];
+    
+    // Screen tracking (via Google Analytics)
+    id<GAITracker> tracker = [[GAI sharedInstance] defaultTracker];
+    if (tracker)
+    {
+        [tracker set:kGAIScreenName value:[NSString stringWithFormat:@"%@", self.class]];
+        [tracker send:[[GAIDictionaryBuilder createScreenView] build]];
+    }
 
     [self.tableView reloadData];
 }