LDAP users + XMPP authentication
This pull request adds 2 features as a starting point for using LDAP for authentication:
- When creating a Plinth user, optionally create an LDAP user as well. The LDAP user will be modified or deleted if the Plinth user is modified or delete. (Enabling/disabling the LDAP user is not implemented yet.)
- Option to switch ejabberd to use LDAP authentication method.
Before testing these changes, the following setup is needed:
- Run setup.d/30_ldap-server script from freedombox-setup.
- Run first-run.d/50_ldap-server script. It's available in the 2nd patch I posted at https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787128.