More clean up
small changes in Broadcast demo settings
allreduce
Handle failures in allreduce
allreduce with new task addition and failed task deletion
update allreduce to merge code from shravan_groupcomm_interfaces
improve hyper cube topology control and fix bugs in handling source dead/add events
merge code from shravan_groupcomm_interfaces
fix comments
add logs
small modifications, commit for merging
allreduce on chunk messages through ReduceScatter+Allgather
refine client control flow
add version control and encode iteration and comm type info to bytes
merge code from shravan_groupcomm_interfaces
handle messages when AllReducer is not running 'apply'
solve errors when sending msgs in onNext and enhance node version control for communication between driver and tasks
create BGD allreduce demo, try to use allreduce but not braodcast/reduce