Improve the cache performance footer info even more

1) /cache/admin.php Setup some cache stores, including some primary / secondary caches, eg localizable caches like course mod info 2) Turn on the perfdebug 3) Clear caches, look at the footer info and confirm everything lines up and looks good.  4) Confirm that the individual primary / secondary cache stores re visible rather than the cache store class name. NOTE: only cache stores that get a read will be shown, so a second / final store may not be shown if there was no misses on the primary cache. 5) Confirm how it is now visible that cache misses on a higher cache (eg static) flow down to the primary and then secondary etc cache stores