Non string eval return

This is a fix for issue #128. evalSHA now works if the script returns a numeric, previously it only worked for strings. Initial fix is to parse using the asAny aggregate and then cast.

Can we improve on asAny? Using receive(singleLineReply) wouldn't work for list replies, so we'd need to handle bulkReply anyway. Either way we end up with the same behaviour as asAny. Suggestions welcome.