Internationalization for public errors

Currently, we throw many public exceptions without proper i18n.
Wrap natural-language error messages in _() so they can be translated.

In the service plugin, raise NotFound errors using handle_not_found helper
so the error message contains the offending service.

Use ScriptError instead of NotFoundError in bindinstance install.

https://fedorahosted.org/freeipa/ticket/1953

ipalib/cli.py

@@ -621,7 +621,7 @@ class textui(backend.Backend):
 
         counter = len(entries)
         if counter == 0:
-            raise NotFound(reason="No matching entries found")
+            raise NotFound(reason=_("No matching entries found"))
 
         i = 1
         for e in entries: