Add delete hotspot button to editor

Signed-off-by: Justin Georgi <justin.georgi@gmail.com>

includes/GlModelHooks.php

@@ -85,9 +85,15 @@ class GlModelHooks {
             'onclick' => 'readMetadata()'
         );
 
+        $delButtonAttr = array(
+            'class' => 'preview-button DeleteHotspots',
+            'onclick' => 'readyDelHotspot()'
+        );
+
         $addHsButton = array(
             Html::rawElement('button',$addButtonAttr,'Add a new hotspot'),
-            Html::rawElement('button',$readButtonAttr,'Update hotspots')
+            Html::rawElement('button',$readButtonAttr,'Update hotspots'),
+            Html::rawElement('button',$delButtonAttr,'Delete hotspot')
         );
 
         $previewHTML = Html::rawElement('div',NULL,$previewViewer.implode($addHsButton));