Add to jberet-rest-api to support restarting by job id (restaring its latest job execution)

Currently one can only start a previous job execution, but often times users need to restart by job id (restarting its latest job execution, without knowing its job execution id). There should be a rest restart api by job id (job name), which behind the scene gets the latest job execution, and if found any eligible one, then restart it.

One benefit is, for a remote client, the new api only need 1 request/response, while the existing api would need 2-3 round trips.