Add support for specifying an LDAP URL.

Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
Remove unnecessary strdup() (and resulting leak)

Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
Add support for specifying bind DN and password.

This uses a seperate hdb-ldap-secret-file configuration value, which
specifies an external file that may be used to supply the LDAP bind dn
and password. This allows that specific file to be configured with more
restrictive permissions than the global krb5.conf.

Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
Document the new hdb-ldap* configuration options.

Signed-off-by: Love Hornquist Astrand <lha@h5l.org>
Add a configuration option to enable LDAP Start TLS.

Signed-off-by: Love Hornquist Astrand <lha@h5l.org>