Reworked sharing of widget's shared/res directory.

Reworked sharing of widget's shared/res directory.

./res/wgt/shared/res directory content was moved to ./shared/res
and then ./res/wgt/shared/res was symlinked to ./shared/res

This broke signatures check for delta update.

Now all items (files and directories) under ./res/wgt/shared/res
are symlinked into ./shared/res, and vice versa.
During delta update these symlinks are removed, so that the
signatures check can complete successfully, and later the symlinks
are recreated again.

Added smoke tests for symlinking shared/res contents in Tizen 3.0

To added tests pass requires:
- https://review.tizen.org/gerrit/#/c/117264/

Change-Id: I9423d78aba5cb338b14a9f8853754e0fa8980e0c