HBASE-12699 undefined method 'setAsyncLogFlush' exception thrown when setting DEFERRED_LOG_FLUSH=>true (Stephen Jiang)
HBASE-9431 Set 'hbase.bulkload.retries.number' to 10 as HBASE-8450 claims
HBASE-5162 Basic client pushback mechanism

Instead of just blocking the client for 90 seconds when the region gets too
busy, it now sends along region load stats to the client so the client can
know how busy the server is. Currently, its just the load on the memstore, but
it can be extended for other stats (e.g. cpu, general memory, etc.).

It is then up to the client to decide if it wants to listen to these stats.
By default, the client ignores the stats, but it can easily be toggled to the
built-in exponential back-off or users can plug in their own back-off
implementations
HBASE-10201 Port 'Make flush decisions per column family' to trunk

Signed-off-by: stack <stack@apache.org>