Add slow offer support on write pressure

When there is write pressure on the penciller and it returns to the
bookie, the bookie will now punish the next PUT (and itself) with a
pause.  The longer the back-pressure state has been in place, the more
frequent the pauses

src/leveled_inker.erl

@@ -122,7 +122,7 @@
 -define(JOURNAL_FILEX, "cdb").
 -define(MANIFEST_FILEX, "man").
 -define(PENDING_FILEX, "pnd").
--define(LOADING_PAUSE, 5000).
+-define(LOADING_PAUSE, 1000).
 -define(LOADING_BATCH, 1000).
 
 -record(state, {manifest = [] :: list(),