Fixes sizing for EXIF-rotated images

See #689 and #691.  Unfortunately those issues don't do a great job of concisely describing the issue.  

Please note this does not address the issue of sizing images with custom rotation with , for example - `requestCreator.rotate(degrees, pivotX, pivotY)`, because the math is not trivial and there should probably be some discussion about the actual desired behavior.

However, I feel like it's still appropriate to make this change because ideally EXIF rotation should be transparent to the developer, whereas `requestCreator.rotate()` would have to be specifically requested.  
It popped up on these lines:

```
targetHeight = targetWidth;
targetWidth = tmpHeight;
```