[VOTE] Commit MAPREDUCE-728 to Hadoop 0.21

[Hong Tang]

MAPREDUCE-728 could not make the code freeze deadline primarily it  
couples closely with JobTracker and that there are quite a few late  
patches that changed the APIs it depend on. It passed testing on  
Hudson on Thursday night. All new changes I added in the latest patch  
(thanks to Chris for his assist in the process) are trivial changes to  
accommodate either API changes or build changes (e.g. avro bumps up  
version from 1.0.0 to 1.1.0).

The patch adds a new MapReduce simulator, Mumak, as a contrib project.  
it has sufficient usage to help us understand, debug, profile, and  
design-proof JobTracker or scheduler.

Given the circumstances, I would like to request a vote to commit  
MAPREDUCE-728 to Hadoop 0.21.

-Hong