Disable asyncDataFetching in ASTableView and ASCollectionView init methods.

It's currently unreliable for some use cases that issue editing calls while
content is displayed or being interacted with.  The performance gain is not
sufficient to sacrifice correctness for the clients that hit this issue,
so it will remain off until fully resolved.

AsyncDisplayKit/ASCollectionView.mm

@@ -136,6 +136,10 @@ static BOOL _isInterceptedSelector(SEL sel)
 {
   if (!(self = [super initWithFrame:frame collectionViewLayout:layout]))
     return nil;
+  
+  // FIXME: asyncDataFetching is currently unreliable for some use cases.
+  // https://github.com/facebook/AsyncDisplayKit/issues/385
+  asyncDataFetchingEnabled = NO;
 
   ASDisplayNodeAssert([layout isKindOfClass:UICollectionViewFlowLayout.class], @"only flow layouts are currently supported");
 
@@ -165,8 +169,10 @@ static BOOL _isInterceptedSelector(SEL sel)
   return self;
 }
 
--(void)dealloc {
-  // a little defense move here.
+- (void)dealloc
+{
+  // Sometimes the UIKit classes can call back to their delegate even during deallocation.
+  // This bug might be iOS 7-specific.
   super.delegate  = nil;
   super.dataSource = nil;
 }