added some doc on the counters+heartbeat functionality
trying to run the PersistSpec sequentially
removed nicta/release as a resolver
fixed the concurrent execution of processes on the same DList
This fix required to change the implementation of the parent/child relationship and store it as an attribute instead of using the members of the Attributable trait
I also changed the implementation of the SeqSource to use the id of the DataSource instead of an incremented one and I'm using the default xstream serialization instead of a custom Array[Byte]
removed some unnecessary imports which fail the CDH3 build
removed the reset method on the configuration
this method was only used to test the 'override' functionality of Text files and checkpoints and is not absolutely necessary to test those