[MONDRIAN-1471]  merge of 6730939, 638a86e, dedd074
Eliminates unnecessary use of Stack, switched to double-check locking of .getMemberReader(), and made QueryTiming threadsafe.
[MONDRIAN-1471] Added a BlockingHashMap implementation, which replaces the ResponseQueue in SegmentCacheManager and MonitorImpl.  The ResponseQueue blocked all threads attempting to fetch their response,
whereas this implementation blocks on the get of individual items within the Map.
(cherry picked from commit d1ccfa4)
Merge pull request #90 from mkambol/lagu-mondrian-1471

[MONDRIAN-1471]  merge of 6730939, 638a86e, dedd074