Use Service Bus Partitioned Queues for improved reliability

Partitioned entities in service bus offer much higher reliability than non-partitioned ones:
http://msdn.microsoft.com/en-us/library/azure/dn520246.aspx

We should be able to specify using partitioined entities in the taskhubdescription on creation of taskhub.

Also, before making this code change we have to make a fork for service bus server since that does not support partitioned entities.