Rename pushover.png -> po.png to match the Channel.kind value

templates/front/channels.html

@@ -196,7 +196,7 @@
         </li>
         {% if enable_pushover %}
         <li>
-            <img src="{% static 'img/integrations/pushover.png' %}"
+            <img src="{% static 'img/integrations/po.png' %}"
                  class="icon" alt="Pushover icon" />
 
             <h2>Pushover</h2>

templates/integrations/add_pushover.html

@@ -166,7 +166,7 @@
         <div class="form-group">
             <div class="col-sm-offset-2 col-sm-10">
                 <button type="submit" class="btn btn-default">
-                    <img class="ai-icon" src="{% static 'img/integrations/pushover.png' %}" alt="Pushover" />
+                    <img class="ai-icon" src="{% static 'img/integrations/po.png' %}" alt="Pushover" />
                     Subscribe with Pushover
                 </button>
             </div>