revising state-based template classes and adding message paragraph styling

apps/openassessment/templates/openassessmentblock/peer/oa_peer_complete.html

 {%  extends "openassessmentblock/peer/oa_peer_assessment.html" %}
 
 {% block list_item %}
-<li id="openassessment__peer-assessment" class="openassessment__steps__step step--peer-assessment is--empty is--complete is--collapsed">
+<li id="openassessment__peer-assessment" class="openassessment__steps__step step--peer-assessment ui-toggle-visibility is--empty is--complete is--collapsed">
 {% endblock %}
 
 {% block title %}

apps/openassessment/templates/openassessmentblock/peer/oa_peer_turbo_mode.html

 {%  extends "openassessmentblock/peer/oa_peer_assessment.html" %}
 
 {% block list_item %}
-<li id="openassessment__peer-assessment"class="openassessment__steps__step step--peer-assessment ui-toggle-visibility is--complete is--collapsed">
+<li id="openassessment__peer-assessment"class="openassessment__steps__step step--peer-assessment ui-toggle-visibility is--complete">
 {% endblock %}
 
 {% block title %}
@@ -117,4 +117,3 @@
     </div>
 </div>
 {% endblock %}
-

apps/openassessment/templates/openassessmentblock/peer/oa_peer_turbo_mode_waiting.html

 {%  extends "openassessmentblock/peer/oa_peer_assessment.html" %}
 
 {% block list_item %}
-<li id="openassessment__peer-assessment" class="openassessment__steps__step step--peer-assessment is--waiting is--complete is--collapsed">
+<li id="openassessment__peer-assessment" class="openassessment__steps__step step--peer-assessment ui-toggle-visibility is--complete">
 {% endblock %}
 
 {% block title %}

apps/openassessment/xblock/static/sass/oa/views/_oa-base.scss

@@ -30,6 +30,14 @@
       @extend %copy-3;
       color: $copy-secondary-color;
 
+      p {
+        margin-bottom: ($baseline-v/2);
+
+        &:last-child {
+          @extend %wipe-last-child;
+        }
+      }
+
       a {
         @extend %link-copy;
       }