Changes to cards in notebook gallery (#422)

* added gallery changes

* addressed PR comments

src/Explorer/Panes/PublishNotebookPaneComponent.tsx

@@ -301,9 +301,9 @@ export class PublishNotebookPaneComponent extends React.Component<PublishNoteboo
                 thumbnailUrl: this.state.imageSrc,
                 created: this.props.notebookCreatedDate,
                 isSample: false,
-                downloads: 0,
-                favorites: 0,
-                views: 0,
+                downloads: undefined,
+                favorites: undefined,
+                views: undefined,
                 newCellId: undefined,
                 policyViolations: undefined,
                 pendingScanJobIds: undefined,

src/Explorer/Panes/__snapshots__/PublishNotebookPaneComponent.test.tsx.snap

@@ -89,8 +89,8 @@ exports[`PublishNotebookPaneComponent renders 1`] = `
             "author": "CosmosDB",
             "created": "2020-07-17T00:00:00Z",
             "description": "",
-            "downloads": 0,
-            "favorites": 0,
+            "downloads": undefined,
+            "favorites": undefined,
             "gitSha": undefined,
             "id": undefined,
             "isSample": false,
@@ -102,7 +102,7 @@ exports[`PublishNotebookPaneComponent renders 1`] = `
               "",
             ],
             "thumbnailUrl": undefined,
-            "views": 0,
+            "views": undefined,
           }
         }
         showDelete={false}