[utils] Added new get method to QueryCache The new get method enables the retrieval an item in the cache by specifying a default value so that in the absence of an item for the key, the default value is returned.

[test/rset] typo

[utils] Fixed issue in clearing QueryCache When trying to add an item in a full QueryCache, the cache tries to make room. It tries to list and remove non-permanent items with a transient counter (number of times it has been requested). However, there is a pathological case where items could be non-permanent but still not have a transient counter because they were added, but never requested. In some cases, the full cache could be flushed, including the permanent items. This changeset attempts to fix this issue by only dropping the non-permanent items that did not hav a transient counter.