Added 'sent' status label in the posts list view

refs https://github.com/TryGhost/Team/issues/954

- This is a first iteration before replacing the status with an email icon in the future. It's meant to signal visually the current status instead of leaving it completely blank

ghost/admin/app/components/gh-posts-list-item.hbs

@@ -70,6 +70,12 @@
                 Published
             </span>
             {{/if}}
+
+            {{#if @post.isSent}}
+            <span class="gh-content-status-published nowrap">
+                Sent
+            </span>
+            {{/if}}
         </div>
     </LinkTo>
 </li>

ghost/admin/app/models/post.js

@@ -153,6 +153,7 @@ export default Model.extend(Comparable, ValidationEngine, {
     isDraft: equal('status', 'draft'),
     internalTags: filterBy('tags', 'isInternal', true),
     isScheduled: equal('status', 'scheduled'),
+    isSent: equal('status', 'sent'),
 
     isPost: equal('displayName', 'post'),
     isPage: equal('displayName', 'page'),

ghost/admin/mirage/factories/post.js

@@ -23,7 +23,7 @@ export default Factory.extend({
     publishedAt: '2015-12-19T16:25:07.000Z',
     publishedBy: 1,
     status(i) {
-        let statuses = ['draft', 'published', 'scheduled'];
+        let statuses = ['draft', 'published', 'scheduled','sent'];
         return statuses[i % statuses.length];
     },
     title(i) { return `Post ${i}`; },