Wrap GraphiQL in <div> and add 'Loading...' message
Wrap GraphiQL in <div> and add 'Loading...' message

Based on https://github.com/graphql/graphiql/commit/d5f027ae851d357c6d83e6b908baba888b5b7282

graphql/express-graphql,graphql/express-graphql,graphql/express-graphql