Abrandoned/ping port health check

significant throughput increase under heavy load by properly working the in-memory queue FIFO instead of LIFO, also swapped out `+` for `concat` on arrays of frames as `+` makes a copy and is up to 100x slower on large message body

client also tracks server being up/down in ThreadSafe Cache that only checks ping port every 2 seconds (plan to make health check interval configurable in future)

@liveh2o @localshred