Fix the problem files get removed when upgrading package

Fix the problem files get removed when upgrading package

Since the sequence of scriptlets being executed
when upgrading a rpm package is as follows,
- (pre of new package)
- (package install)
- (post of new package)
- (preun of old package)
- (removal of old package)
- (postun of old package)
files should not be removed at preun stage
unless a package upgrade is performed.
And since the previous "mv" method generates warning
when erasing package, as the installed files are
already moved to other directories, we are now using
symbolic links instead of moving files.

Change-Id: I0fd4a9173c9f74170ac05c2b0bc4f378de728195