[Feature Request] Command timeout

I know that this project is somewhat a replica of the awesome cronic tool. But I'd like to suggest a feature that would be greatly useful for me and possibly to others.

I use cron to start a ton of jobs, especially backup ones. In some rare cases, the process got stuck, or for problems on the filesystem, network, or whatever problem. Would be awesome to have an option to define a timeout for a command, which would kill the process(Using some methods specified by the command line arguments) and the output would be sent by cron to the root email.

If this makes sense, I'd be happy to implement it and push a PR.