Meta server: create and pass chunk server and chunk access tokens with chunk allocation request to the write master to allow to setup synchronous replication chain. Create chunk server "authenticated user id" with reduced sha1 hash or the chunk server authenticated name and server location. Use this id to create chunk server and chunk access tokens with chunk server communications, synchronous or asynchronous replications, chunk recovery etc.
Minor optimization use statically created temporary ostringstream objects in the rpc processing in non re-entrant code paths.
Kfsio: add type definition for sequence token type with delegation and chunk access tokens.
Meta server: fix write lease renew by using appropriate chunk access token flags.