GraphQL: Create a generic query node type for pagination

GitHub's current GraphQL API supports a generic `query.resource` type:

```js
query {
resource(url:"https://github.com/gr2m/sandbox") {
... on Repository {
nameWithOwner
}
}
}
```

It would be great to have a generic node type that would allow for pagination.

```js
query($cursor: String) {
paginate(first: 100, after: $cursor) {
pageInfo {
endCursor
hasNextPage
}
nodes {
... on Repository {
nameWithOwner
}
}
}
}
```

That would greatly simplify to paginate complex queries with multiple, nested paginations