Fix Bootstrap theme for MediaWiki 1.28

[yaypaul]

Had some trouble integrating Bootstrap theme with the latest build of MediaWiki, these tweaks did the trick.
Replace wfMsg() with wfMessage()
Replace $article->getRawText() with $article->getContent(Revision::RAW)

[Reception123]

anyone?

[bschwenk]

@yaypaul I required further changes in order to make this work with 1.28.1 (line 481):

	$article = new WikiPage($pageTitle);
	$wgParserOptions = new ParserOptions($wgUser);
	$content = $article->getContent(Revision::RAW);
	$parserOutput = $wgParser->parse($content->mText, $pageTitle, $wgParserOptions);
	echo $parserOutput->getText();