Maintenance script for Bugid 13714

BugID: 13714 - Modify local navigation parsing
This maintenance script goes through MediaWiki:Wiki-navigation
message on given wiki, replacing
'blogs-recent-url-text',
'blogs-recent-url',
'portal-url',
'forum-url'
with their respective translations.

@lgarczewski, @mroszka, @kamilkoterba - I'll greatly appreciate your feedback :)