Make colors optional in nvd3 visualizations

client/src/mvc/dataset/dataset-edit-attributes.js

@@ -5,7 +5,6 @@ import Backbone from "backbone";
 import { getAppRoot } from "onload/loadConfig";
 import { getGalaxyInstance } from "app";
 import _l from "utils/localization";
-// import Utils from "utils/utils";
 import Tabs from "mvc/ui/ui-tabs";
 import Ui from "mvc/ui/ui-misc";
 import Form from "mvc/form/form-view";

client/src/mvc/visualization/chart/views/settings.js

@@ -2,8 +2,8 @@
 import _ from "underscore";
 import Backbone from "backbone";
 import Utils from "utils/utils";
-import FormDisplay from "components/Form/FormDisplay";
 import FormData from "mvc/form/form-data";
+import FormDisplay from "components/Form/FormDisplay";
 import { appendVueComponent } from "utils/mountVueComponent";
 
 export default Backbone.View.extend({

config/plugins/visualizations/nvd3/nvd3_bar/config/nvd3_shared.xml

@@ -26,6 +26,7 @@
             <label>Pick a series color</label>
             <name>color</name>
             <type>color</type>
+            <optional>true</optional>
         </input>
         <input>
             <label>Column of data point labels</label>