Merge pull request react-native-maps#333 from joelcloralt/master

Fix warning for iOS "loadImageWithTag is deprecated" for RN 0.28.0

Author: jrichardlai

ios/AirMaps/AIRMapMarker.m

@@ -209,9 +209,10 @@ - (void)setImageSrc:(NSString *)imageSrc
         _reloadImageCancellationBlock();
         _reloadImageCancellationBlock = nil;
     }
-    _reloadImageCancellationBlock = [_bridge.imageLoader loadImageWithTag:_imageSrc
+    _reloadImageCancellationBlock = [_bridge.imageLoader loadImageWithTag:[RCTConvert NSURLRequest:_imageSrc]
                                                                      size:self.bounds.size
                                                                     scale:RCTScreenScale()
+                                                                    clipped:YES
                                                                resizeMode:UIViewContentModeCenter
                                                             progressBlock:nil
                                                           completionBlock:^(NSError *error, UIImage *image) {