Fixed header center on Likert and OneDScale.

src/app/Cockpit.Experiments.Web/App/Components/Questions/LikertScale/LikertScale.html

 <div class="container-fluid LikertScale">
 	<div class="row">
-		<div class="col-xs-offset-2 col-xs-10">
+		<div class="" data-bind="css: IsStimuliBlockVisible ? 'col-xs-offset-2 col-xs-10' : 'col-xs-12'">
 			<h3 data-bind="html: HeaderLabel" class="QuestionHeader"></h3>
 		</div>
 	</div>

src/app/Cockpit.Experiments.Web/App/Components/Questions/OneDScale/OneDScale.html

 <div class="container-fluid OneDScale">
 	<div class="row">
-		<div class="col-xs-offset-2 col-xs-10">
+		<div data-bind="css: IsStimuliBlockVisible ? 'col-xs-offset-2 col-xs-10' : 'col-xs-12'">
 			<h3 data-bind="html: HeaderLabel" class="QuestionHeader"></h3>
 		</div>
 	</div>