Refine scan app delta

Refine scan app delta

1) Logging more precisely
2) Add missing cases e.g., worse riskiest when history is exist and no new
   malware detected and worse case exists
3) Remove useless param on judge stage: jHistory
   jHistory is always same to history.
4) Insert worst when history riskiest case either because existing
   history(worst) needs to be updated when the file is modified and
   malware is detected samely.
5) Delete db row whenever the file is newly scanned regardless of new
   malware detection from the file. It's for refreshing db row when file
   is newly scanned.

Change-Id: Iba88c3e0ed96bd8413a10fcd9aa556edc7129f60
Signed-off-by: Kyungwook Tak <k.tak@samsung.com>