CON-2228: NS_MAIN articles redirecting to categories rendered in Venus

WikiaPageType::isArticlePage - follow redirects
WikiaPageTest: introduce getTitle private method

* getTitle follows redirects
* code cleanup
Merge branch 'CON-NewArticle' into CON-2228-wikia-page-type-follow-redirects
CON-2228: fix unit tests
Merge pull request #5531 from Wikia/CON-2228-wikia-page-type-follow-redirects

CON-2228: NS_MAIN articles redirecting to categories rendered in Venus