apt: Add a new unattended_extra_origins option

Setting unattended_extra_origins lets you add extra origins to the
unattended-uprades whitelist.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
bcfg2: Split comma separate values on ", "

This allows values to contain commas (like LDAP DN) without being
considered as a list.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
sssd: Add initial templates

This adds templates for sssd.conf, smb.conf and krb5.conf.

Basic configuration options are available.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>