Create a CRC16 checksum from the bytes. implementation is from mp911de/lettuce, modified with some more optimizations @param bytes @param s @param e @return CRC16 as integer value See <a href="https://github.com/xetorthio/redis/pull/733#issuecomment-55840331">Issue 733</a>
CRC16 Implementation according to CCITT standard Polynomial : 1021 (x^16 + x^12 + x^5 + 1) See <a href="http://redis.io/topics/cluster-spec">Appendix A. CRC16 reference implementation in ANSI C</a>