KNL-1225 SiteCacheImpl is incompatible with distributed/JSR-107 caching
This leaves the old SiteCacheImpl in place when using legacy MS and adds a new one for use with the JSR-107 MS



git-svn-id: https://source.sakaiproject.org/svn/kernel/trunk@308862 66ffb92e-73f9-0310-93c1-f5514f145a0a