Add demo mode function.

Squashed commit of the following:

commit 718efd4db1fd64e5baed53d27c149219fab47879
Author: Anže Žitnik <anze.zitnik@xlab.si>
Date:   Thu Jan 20 16:03:58 2022 +0100

    Version up

commit c574b33acd9c5c131e8a2b53ad69ff1a970d2203
Author: Anže Žitnik <anze.zitnik@xlab.si>
Date:   Thu Jan 20 16:02:07 2022 +0100

    Add demo mode function.

    Created an option in constants.json where demo mode can be selected. It will not query wazuh or elastic, just output random evidence.