Add buttons for list entries

As part of updating the stylesheet, moved `.button-secondary` to the
global stylesheet, since this is not related to list entries but instead
affects all buttons with that class (this class wlil be removed once all
the buttons are using the new macro).

app/assets/stylesheets/components/list-entry.scss

@@ -6,8 +6,12 @@
     position: relative;
   }
 
-  .list-entry-remove {
-    @include core-19;
+  &__button--remove,
+  &__button--add {
+    width: auto;
+  }
+
+  &__button--remove {
     display: block;
     margin-bottom: 15px;
     margin-top: 5px;
@@ -23,6 +27,10 @@
     }
   }
 
+  &__button--add {
+    margin: 0 0 20px 0;
+  }
+
   .form-control {
     padding-left: 1.84em;
     width: 100%;
@@ -45,12 +53,4 @@
     pointer-events: none;
   }
 
-  .list-entry-add {
-    @include core-19;
-    margin: 0 0 20px 0;
-  }
-}
-
-.button-secondary {
-  @include button($grey-3);
 }