Scripting/scheduler (cronjob)

[vilhelmprytz]

Is your feature request related to a problem? Please describe.
It's tedious to write backup scripts, task schedulers etc.

Describe the solution you'd like
I would like Wilfred to be able to schedule tasks, either for one-time use or for recurring periodic use (e.g. cronjob) and have a set of built-in tasks such as managed backups. Perhaps this should be implemented as an extension (see #34) but I believe that this could be implemented directly to Wilfred for now and then separated once the extension system is implemented.

Describe alternatives you've considered
None.

Additional context
This feature would make it possible to schedule backups and fix #24