removeCache fails for caches with a SingleFileStore

If DefaultCacheManager.isRunning("foo") returns true, and "foo" has an associated SingleFileStore, calling DefaultCacheManager.removeCache("foo") tosses an NPE and isRunning("foo") continues to return true, even though the cache is in a TERMINATED state. I can avoid the NPE by stopping the cache before calling removeCache, but isRunning will still incorrectly return true.