Dictionary Ordering

@vokalinteractive/ios-developers Code review please?

Also, will need to be tagged `0.1.1` when it's merged.
My suggestion would be to change the function signature so you can call
`[keyDataByKey.allKeys sortedArrayUsingFunction:CompareNSData context:NULL];`
You'd need to add an (unused) `void *` "context" parameter.
That seems cleaner than wrapping the function in a comparator block.