Enhance db dump performance

BufferedOutputStream can enhance db dump performance.
Especially, if the data for dump is bigger
and the dump is being processed in the main thread,
it could cause ANR for slow performance.

Change-Id: Ia9c8f0ca22e0b829ee983a3cb78e9757654b9a35
Signed-off-by: jangwon.lee <jangwon.lee@lge.com>