Wire up mode buttons to mode routes; Expose displayName;

modes/example/src/index.js

@@ -1,6 +1,7 @@
 export default function mode({ modeConfiguration }) {
   return {
     id: 'example-mode',
+    displayName: 'Basic Viewer',
     validationTags: {
       study: [],
       series: [],

modes/longitudinal/src/index.js

@@ -20,6 +20,7 @@ export default function mode({ modeConfiguration }) {
     // TODO: We're using this as a route segment
     // We should not be.
     id: 'longitudinal-workflow',
+    displayName: 'Comparison',
     validationTags: {
       study: [],
       series: [],