Update to comments for 508 compliance with translation (#2386)

* 508 fixes to bring the comments table into compliance. The <thead> element must be visible to users and <th> must display text that indicates what resides in the columns below.

* Updated to properly use the i18 translation

ng2-components/ng2-activiti-tasklist/src/components/comment-list.component.html

@@ -3,7 +3,7 @@
     (rowClick)="selectComment($event)" *ngIf="hasComments()">
 
     <data-columns>
-        <data-column key="createdBy">
+        <data-column key="createdBy" title="{{'TASK_DETAILS.COMMENTS.CREATED_BY_HEADER' | translate }}">
             <ng-template let-entry="$implicit">
                 <div id="comment-user-icon"
                 class="adf-comment-img-container">
@@ -18,7 +18,7 @@
                 </div>
             </ng-template>
         </data-column>
-        <data-column key="message">
+        <data-column key="message" title="{{'TASK_DETAILS.COMMENTS.MESSAGE_HEADER' | translate }}">
             <ng-template let-entry="$implicit">
                 <div class="adf-comment-contents">
                     <div id="comment-user" class="adf-comment-user-name">

ng2-components/ng2-activiti-tasklist/src/components/comment-list.component.scss

@@ -53,9 +53,6 @@
         }
 
         &-datatable /deep/ table {
-            thead {
-                display: none;
-            }
             border: none !important;
             tbody td {
                 padding: 0px !important;

ng2-components/ng2-activiti-tasklist/src/i18n/en.json

@@ -46,6 +46,8 @@
             "NONE": "No comments",
             "ADD": "Add a comment",
             "HEADER": "Comments",
+            "CREATED_BY_HEADER": "Created by",
+            "MESSAGE_HEADER": "Message",
             "DIALOG": {
                 "TITLE": "New comment",
                 "LABELS": {