MetricsLogger

Simple implementation of metrics logger with next constraints:

1. no blocking on worker threads
2. metrics only of arithmetic types
3. one metrics is written only by one thread

Benchmark                     Time             CPU   Iterations
---------------------------------------------------------------
BM_wo_logger                662 ns          662 ns      1061318
BM_taylor_logger            886 ns          886 ns       796535
BM_taylor_glog             4303 ns         4302 ns       162679
BM_taylor_atomic_upd        671 ns          671 ns      1049589
BM_taylor_mutex_upd         725 ns          725 ns       960519
BM_taylor_map_upd           944 ns          943 ns       744620
BM_caesar_logger          52965 ns        52963 ns        13206
BM_caesar_wo_logger       52636 ns        52635 ns        13284
DoNothing                  4.74 ns         4.74 ns    112688754