codec-memcache: increase default buffer size and only encode extras if set.
Hide protocol detail from users
readableBytes() ==0 -> !isReadable()
Also record retain() and release()
Fix a buffer leak in BinaryMemcacheObjectAggregatorTest
Fix a buffer leak in BinaryMemcacheObjectAggregatorTest
Fixed various buffer leaks in FixedCompositeByteBufTest
Fixed buffer leaks in LoggingHandlerTest