call stopped callback on the process data
add a small delay to the test example
set state in process_started()
call _process_started instead of process_started
call process_started, call started callback on process_data
implementing before_start()
remove duplicate attributes, ensure uuid cannot be modified
adding before_spawn_process
bugfix to failed_tasks, better error message for failure
workaround for #118, job types terminated due to SIGINT are stuck in the config