add "null" algorithm server ( nullalgo )

+ nullalgo support update_{random,cht}, query_{random,cht}
+ update_* receive datum and return 'true' anyway
+ query_* return fixed string_values datum
+ nullalgo ignore set_config, load, save, get_status
  ( these are only stubs to compile )
add rpc-bench ( nullalgo client for benchamrk )

+ add rpc-bench ( nullalgo client for benchmark )
+ add mixable stub to nullalgo ( mixable support required to run )
+ add nullalgo config stub ( required to run )
add: rpc-bench: measuring throughput and latency