Fix 2q cache bug

When 2q cache became max allowed size and all records are used NullPointer is thrown because LRUList can't find record to remove it.
This patch fix this but in such way.
When all record are used LRUList return null.
When 2q determine that returned record are null it should change max size to allow storing more records.
This behaviour can be managed using new properties in OGlobalConfiguration