Fix StepDeltaPatch

Fix StepDeltaPatch

This patch modifies StepDeltaPatch step that it will remove
installer generated icons for web applications from temporary
directory before it applies patch and checks signature.

Reference package content for applying delta changes is taken
from installation location of package so we copy not only package
files but also installer generated files that are not in signature.

Problematic directory is /shared/res/ where there are package files
and installer generated files.

Requires:
 - https://review.tizen.org/gerrit/69115

To verify, run:
 $ /usr/bin/wgt-backend-ut/smoke-test --gtest_filter=SmokeTest.DeltaMode_Hybrid

Change-Id: Iee5a6561164e9cfb161e8e41a65aedec71b85e54