Restore manager.execute.started and completed events, now for cli execute command
Refactor memusager and cron_env to use manager.execute.started/completed events
Merge branch 'cli_subcommands' of github.com:Flexget/Flexget into cli_subcommands
Fix manager.execute.started/completed events
Add manager.daemon.started/completed events
Change task_start and exit phases to only run once, even if the task is rerun multiple times
Update the plugins dealing with reruns
Make sure plugins don't call manager.shutdown prematurely