Bootstrap: Include two keys below into the same file

- Download public keys and assemble authorized_keys.
- Create .ssh folder and set permissions.
- Add missing comma.

Fixes #32
Bootstrap: Include two keys below into the same file

- Move common/authorized_keys.yml content into common/bootstrap.yml;

Amend b857a3d
Ref #32
Bootstrap: Include two keys below into the same file

- Always add a `\n` separator between files;

Amend b857a3d
Ref #32
Install and configure postfix.
Add empty line.