Generate subject list for webview in "config" API

Going to http://localhost:6543/config will return this:

```
{
  "subjects": [
    {"id": 1, "name": "Arts"},
    {"id": 2, "name": "Business"},
    {"id": 3, "name": "Humanities"},
    {"id": 4, "name": "Mathematics and Statistics"},
    {"id": 5, "name": "Science and Technology"},
    {"id": 6, "name": "Social Sciences"}
  ]
}
```