SERVICES: added support for LDAP service

- Added gen/send/slave scripts for LDAP service.
- Enabled LDAP service in our main slave script.
- Added ldifdiff a ldifsort scripts from CPAN contrib used by our slave script.
- Added empty pre script with local settings about ldap (authz).
- Added password manager for LDAP (can be used on it's own or by our default pw-manager).
  Return codes and interface are the same as our pw-manager.
- Added empty pw-manager config file.

Package "libnet-ldap-perl" must be installed on a machine, where pw-manager or slave script runs.

For service LDAP to work, destination LDAP must have included schemas:
"inetUser" and "perunEduroamUser".