Move .matplotlib dir to /var/cache/karaage

Was /var/www/.kgmatplotlib for some cases and /var/www/.matplotlib for
others.

We shouldn't be using /var/www in the first place.

Change-Id: I9a6c5f4e6bb84ff8f4be046ca7814f95a999ada8
Version 2.7.8-1

Change-Id: I0dca9c3509b1996a471ee49261b99dd764add56c