中文迭代日志

Fix

• Fix(file-integrality): update the process to the database only if all buffers on output-stream or system have been flush and sync to device successfully to avoid resume on the wrong point raise complete file, not integrality. Closes #745
• Fix(clear): fix FileDownloader#clearAllTaskData not clear connection table. Closes #754

Enhancement

• Import Performance: optimize the default output-stream with buffered-output-stream, now the VM buffers length is 8192 bytes.