Improve handling of file URLs for ASNetworkImageNode.

Details discussed in #1003.  This PR supercedes that one.

Author: Scott Goodson

AsyncDisplayKit/ASNetworkImageNode.mm

@@ -188,14 +188,23 @@ - (void)_lazilyLoadImageIfNecessary
         ASDN::MutexLocker l(_lock);
 
         dispatch_async(dispatch_get_main_queue(), ^{
-          _imageLoaded = YES;
-
           if (self.shouldCacheImage) {
-            self.image = [UIImage imageNamed:_URL.path];
+            self.image = [UIImage imageNamed:_URL.path.lastPathComponent];
           } else {
+            // First try to load the path directly, for efficiency assuming a developer who
+            // doesn't want caching is trying to be as minimal as possible.
             self.image = [UIImage imageWithContentsOfFile:_URL.path];
+            if (!self.image) {
+              // If we couldn't find it, execute an -imageNamed:-like search so we can find resources even if the
+              // extension is not provided in the path.  This allows the same path to work regardless of shouldCacheImage.
+              NSString *filename = [[NSBundle mainBundle] pathForResource:_URL.path.lastPathComponent ofType:nil];
+              if (filename) {
+                self.image = [UIImage imageWithContentsOfFile:filename];
+              }
+            }
           }
-
+          
+          _imageLoaded = YES;
           [_delegate imageNode:self didLoadImage:self.image];
         });
       }