refactor: Reorganize Firebase configuration

Sources/Earthquake Network/AppDelegate.m

@@ -51,9 +51,8 @@
     
     [EQNUser defaultUser];
     [EQNManager defaultManager];
-    [FIRApp configure];
-    [FIRMessaging messaging].delegate = self;
     [FBSDKApplicationDelegate.sharedInstance application:application didFinishLaunchingWithOptions:launchOptions];
+    [self configureFirebase];
     
     // add some generic logs for Crashlytics
     NSString *language = [[NSLocale preferredLanguages] firstObject];
@@ -204,6 +203,12 @@
     }];
 }
 
+- (void)configureFirebase
+{
+    [FIRApp configure];
+    [FIRMessaging messaging].delegate = self;
+}
+
 #pragma mark - FIRMessagingDelegate
 
 - (void)messaging:(FIRMessaging *)messaging didReceiveRegistrationToken:(NSString *)fcmToken