Remove rename call in log cleanup

It turns out "rename" is not portable between Ubuntu & Fedora.
Replace the rename calls with equivalent find/mv combinations which
should be portable everywhere.

There is a slight reorganization here to make things hopefully
clearer:

 - consolidate a separate chown done for $BASE/logs/etc into the
   chown -R for it's parent directory
 - add a comment explaining why we're renaming
 - catch all .log files to rename (in old/new/grenade/etc) with one
   global find statement over $BASE/logs
 - then do more specific renames of files in known subdirectories

Change-Id: Ia6466ed34323ab00b4d01ca928c66d2ea2fb3092
Merge "Remove rename call in log cleanup"