Ruby schema.single_object_schema_fingerprint is reversed

The Ruby schema.single_object_schema_fingerprint method (originally added in this PR) seems to return an incorrect fingerprint, which is reversed from what the Java implementation returns.

I believe that the cause is the unnecessary reverse array traversal order on this line during the bit masking + shifting operation for converting the fingerprint into a little endian byte array.

I'll also drop a comment in the original PR that implements this Ruby functionality and see if there's more to the story.