Add support for pagination

[CharlesMassry]

GraphQL spec requires pagination query, which ruby-graphql supports, to be in form of:

    query {
        vendors(first: 5) {
          edges {
            node {
              id
              name
              ingredients {
                name
                quantity
              }
            }
            cursor
          }
          pageInfo {
            endCursor
            hasNextPage
            hasPreviousPage
            startCursor
          }
        }
      }

This fixes that issue, now this commit will remove the N+1 query that was previously present from this GraphQL query

[nettofarah]

This is beautiful!
I'm in Berlin right now with a pretty spotty internet connection. But I should be able to merge this sometime in the next couple of days

[CharlesMassry]

No worries. Actually I'm a little concerned, it doesn't seem to be working with my project although that could due to my configuration, I'm relatively new to GraphQL

[nettofarah]

No worries, @CharlesMassry. I'm gonna check out the branch locally and play with it a bit.
I might push a few extra commits if I run into problems.

Btw, when you said this is the GraphQL standard, did you mean GraphQL or Relay?

[CharlesMassry]

Actually now that I think about it, it looks like the Relay spec, either way the ruby-graphql library supports that

[nettofarah]

I'm thinking this is what you meant: https://facebook.github.io/relay/graphql/connections.htm

[CharlesMassry]

Yeah, that's it, also this http://graphql-ruby.org/relay/connections which automatically adds the pageInfo queryable fields

[nettofarah]

Perfect. Just wanted to make sure we're talking about the same thing.

[nettofarah]

@CharlesMassry: closing this so we can merge our changes together: #4

[nettofarah]

Thanks a lot, @CharlesMassry.
Just merged your change.

[nettofarah]

Btw, just gave you super powers on this repo! 💪