[4.5] Setup cron for mailing and grab entries.

[rizomaa]

• Install package (cron)

• Cron config

• Cron config 2

• Add file path with script for devilery

• Add schedule each month, day 5.

Server: Ubuntu 18 LTS Server

[wellemut]

I think this is similar to the improvements here: kartevonmorgen/openfairdb#259 (review)

[rizomaa]

@wellemut here is a bit different. we stick only to a subscription extension here.

[rizomaa]

sendgrid.com