Bug 11842 - fix framework caching with memcache/plack

Bug 11842 - fix framework caching with memcache/plack

This changes the existing framework caching, which was using memoisation
if memcached was available, and memory in all cases, to use the
Koha::Cache system. This uses memcache if possible, and in-memory
otherwise. However it also clears the cache when the framework updates,
making sure that the changed version will be picked up.

Note that the in-memory cache clears itself after 10 seconds, so that if
memcached isn't available, this is the longest that old versions will
hang around.

Test plan:
* work through
  http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=11842#c0
  and make sure that the erronious result doesn't occur.

Note:
* The patch on bug 12041 is required for this to work.

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>