implement job abort
In the job_detail and job_list need to have an 'Abort' button for all jobs that are not in the DONE state. Pushing this button should switch the job state to 'ABORTING' and notify the controller (which will ultimately switch the state to 'DONE').
Note: the current job state machine cannot handle abort and remove concurrently. Therefore the 'Delete' button should be disabled until the job is terminated.
Note: switching state to 'ABORTING' must be done atomically (only if state is != DONE)