Bug 7248 Added caching support and and moved Caching into Koha namespace

Unit test for Koha/Cache.pm (which includes Koha/Cache/Memcached.pm)

Note that in order to test Koha::Cache you must export the environment variable
MEMCACHED_SERVERS. For example:
$ export MEMCACHED_SERVERS=127.0.0.1:11211

Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>