Fixes job ids in table view

The job id should be taken from job directly (not mapReduceJobState, which isn't available in pig's locale mode).
Updates DAGNode to avoid serializing successor nodes

We only need the successorNames, not successors themselves. This commit adds @JsonIgnore to successors field and updates unit test and demo data.
Improves header comment of demo.pig script

I've included example invocations along with settings needed to store jobs and events json.
Cleans up AmbrosePigProgressNotificationListener fields

I've removed an unused internal enum which we'd missed during the model refactoring.
Adds scriptId argument to call to statsWriteService.sendDagNodeNameMap(…)