* differenciate MemcachedDict for different ERP5 instances by using SharedDict instead of MemcachedDict just same as portal_memcached.getMemcachedDict().
* since encoding key is done in MemcachedTool level, there is no need to do the similar thing in DistributedRamCache level.
* stop diffentiate caches by cache plugin url, because it makes the key too long and it still cannot prevent cache duplication when a user modifies the configuration of cache plugins.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@29534 20353a03-c40f-0410-a6d1-a30d3c3de9de