[add] scheduler: Add 'jitter' option to slightly randomize scheduled execution times.
[add] scheduler: Add 'jitter' option to slightly randomize scheduled execution times.

crawln45/Flexget,Flexget/Flexget,malkavi/Flexget,Flexget/Flexget,malkavi/Flexget,crawln45/Flexget,Flexget/Flexget,malkavi/Flexget,crawln45/Flexget,malkavi/Flexget,ianstalk/Flexget,ianstalk/Flexget,ianstalk/Flexget,Flexget/Flexget,crawln45/Flexget