Fix icon color and btn-group alignment of discussion buttons

app/assets/stylesheets/pages/note_form.scss

@@ -249,13 +249,12 @@
       width: 100%;
       padding-right: 5px;
     }
-
   }
 
   .discussion-actions {
     display: table;
 
-    .new-issue-for-discussion path {
+    .btn-default path {
       fill: $gray-darkest;
     }
 

app/assets/stylesheets/pages/notes.scss

@@ -466,6 +466,10 @@ ul.notes {
   float: right;
   margin-left: 10px;
   color: $gray-darkest;
+
+  .btn-group > .discussion-next-btn {
+    margin-left: -1px;
+  }
 }
 
 .note-actions {