no inspect button for preset categories

fixes #1100

data/presets/categories.json

@@ -2,6 +2,7 @@
     "geometry": "line",
     "icon": "highway",
     "id": "Road",
+    "icon": "category-roads",
     "members": [
         "highway/residential",
         "highway/motorway",

js/id/ui/preset_grid.js

@@ -286,7 +286,10 @@ iD.ui.PresetGrid = function(context, entity) {
                 .attr('class','label')
                 .text(name);
 
-            entered.append('button')
+            entered.filter(function(d) {
+                    return !d.members;
+                })
+                .append('button')
                 .attr('tabindex', -1)
                 .attr('class', 'preset-help')
                 .on('click', helpClick, selection)