Clean up i18n strings

This patch switches to named ("%(name)s") instead of positional ("%s")
substitutions for internationalized strings, so translators can
reorder the words.
This fixes https://fedorahosted.org/freeipa/ticket/2179 (xgettext no
longer gives warnings).

Also, some i18n calls are rewritten to translate the template before
substitutions, not after.

ipalib/plugins/config.py

@@ -241,8 +241,8 @@ class config_mod(LDAPUpdate):
                         continue
                     if obj_attr not in new_allowed_attrs:
                         raise errors.ValidationError(name=attr,
-                                error=_('%s default attribute %s would not be allowed!') \
-                                % (obj, obj_attr))
+                                error=_('%(obj)s default attribute %(attr)s would not be allowed!') \
+                                % dict(obj=obj, attr=obj_attr))
 
         if 'ipaselinuxusermapdefault' in options and options['ipaselinuxusermapdefault'] is None:
             raise errors.ValidationError(name='ipaselinuxusermapdefault',