Allow job serialisation to be customisable

[OmegaPhil]

Currently the upstart service definition launches anacron with '-s', which serialises its jobs - this defeats part of the purpose of running it for me (cron.daily/weekly/monthly will serialise jobs just fine courtesy of run-parts) - I have submitted a similar bug to Debian where its easy to update the '/etc/default/anacron' to fix the behaviour and get parallel jobs (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=743448).

I'm not familiar with upstart, so I've simply edited '/etc/init/anacron.conf' in place on my server - please can anacron's job serialisation be made configurable?

Thanks

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anacron Version: 2.3-19ubuntu2
Ubuntu details:
Description: Ubuntu 13.10
Release: 13.10