Check against self class in initialize methods

Author: dbeard

ios/CodePush/CodePush.m

@@ -61,8 +61,10 @@ @implementation CodePush {
 
 + (void)initialize
 {
-    // Use the mainBundle by default.
-    bundleResourceBundle = [NSBundle mainBundle];
+    if (self == [CodePush class]) {
+        // Use the mainBundle by default.
+        bundleResourceBundle = [NSBundle mainBundle];
+    }
 }
 
 #pragma mark - Public Obj-C API

ios/CodePush/CodePushConfig.m

@@ -20,7 +20,9 @@ + (instancetype)current
 
 + (void)initialize
 {
-    _currentConfig = [[CodePushConfig alloc] init];
+    if (self == [CodePushConfig class]) {
+        _currentConfig = [[CodePushConfig alloc] init];
+    }
 }
 
 - (instancetype)init