revising grade's header to always be prominently displayed visually

apps/openassessment/templates/openassessmentblock/grade/oa_grade_waiting.html

 {% spaceless %}
-<li id="openassessment__grade" class="openassessment__steps__step step--grade is--waiting">
+<li id="openassessment__grade" class="openassessment__steps__step step--grade">
     <header class="step__header ui-toggle-visibility__control">
         <h2 class="step__title">
             <span class="wrapper--copy">