Added 'backup' and 'restore' scripts with plays

- 'backup.sh' script allows you to back up to localhost sensitive data
  from remote hosts, like SSH host keys, monkeysphere GnuPG keys, etc.;

- 'restore.sh' should be used just after installation of a host and
  configuration of sudo access, it uses data backed up by 'backup.sh' and
  restores them in proper place with correct ownership and permissions;

- restore script *should* be safe to run during normal operation, but
  take care to create backups first. By default 'restore.sh' requires
  a hostname to work on;

- both backup and restore scripts use respective Ansible playbooks,
  which in turn are including tasks from separate task files in each
  corresponding role (sshd, monkeysphere, sslcerts);