Create overload FSM, relay checkins through it
Export type elysium_connection:buffering(); fix elysium_overload:checkin
Handle buffered query_requests via one checkin piggyback
Move pending requests queue to ets_buffer from elysium_overload state
Removed FSM for overload buffer, using elysium_bs_serial instead
Debug messaging with elysium_bs_serial (default buffering strategy)
Labeled bs_serial messages so they aren't confused
Merge pull request #2 from jaynel/TS-864.request.buffering

[TS-864] Buffer requests when there aren't enough sessions