Added CGImageRelease call in encoding example
Added CGImageRelease call in encoding example

Added CGImageRelease call following CGImageRetain call in the encoding usage example to demonstrate good practice of lowering the reference count of an object after use.

TheLevelUp/ZXingObjC,benjohnde/ZXingObjC,benjohnde/ZXingObjC,TheLevelUp/ZXingObjC