Meta server: change chunk server heartbeat and chunk directory info RPC short version to still use decimal notation for all key value pairs, in order to maintain backward compatibility with web ui. Fix short field names.
Chunk server fix short RPC handshake, change chunk directory and heartbeat RPC to use decimal notation with short version instead of hex, in order to maintain backward compatibility with web ui. Change chunk directory info RPC to always send both short and long versions of the headers in order to simplify logic, by avoid RPC version conditional.