Mongokit explore resources

**Data Review cancel/save edit-summary issue is resolved:**

- Added ```-- Select --``` as default ```<option>``` in dropdown list.
- The size of table is made scrollable, to fit inside the browser viewport.

**After taking this pull what to test:**

- Go to ```File``` app --> ```Data Review```.
- Click on any row's Edit button. And without changing any of the field, click on Cancel button.
In this case editing fields should get hidden and Edit button should reappear without any edit-summary-alert.