Allow re-send of messages in msg detail view on OutgoingKeyError

We also show more errors than we used to in the MessageDetail screen
to help make it clear what is happening, and why the user would need to
re-send.

FREEBIE

background.html

@@ -293,6 +293,14 @@
   <script type='text/x-tmpl-mustache' id='message-detail'>
     <div class='container'>
       <div class='message-container'></div>
+      {{ #allowRetry }}
+        <div class='retries'>
+          <div>{{ retryDescription }}</div>
+          {{ #retryTargets }}
+            <button class='retry gray' data-number='{{ number }}'>{{ title }}</button>
+          {{ /retryTargets }}
+        </div>
+      {{ /allowRetry }}
       <div class='info'>
         <table>
           {{ #errors }}