Fix 'mod_ldap missing' loading mod_authnz_ldap

[Tue Sep 09 10:40:20.589086 2014] [authnz_ldap:error] [pid 27819] AH01749: Module mod_ldap missing. Mod_ldap (aka. util_ldap) must be loaded in order for mod_authnz_ldap to function properly
AH00016: Configuration Failed

fix quotes