Fix broken i18n support

In notification and publisher.rpc module, there are some log messages
don't support i18n, this patch fixes them.

NOTE: rename unused variable from _ to n, because it will overshadow
global _ of gettext.

Change-Id: Ic703fe6536234f4d51a84f4a3b2e04049ec6f3b5
Closes-Bug: #1263711
Merge "Fix broken i18n support"