Deploy GraphQL Playground Server

[albrow]

Similar to https://meshmock.spaceship.0x.org/, we need to deploy a server that uses Mesh v10 and real data. This should include:

1. SSL/HTTPS
2. A good domain name
3. Basic rate-limiting

Mesh v10 includes the playground built-in. Just set the environment variables ENABLE_GRAPHQL_SERVER=true and ENABLE_GRAPHQL_PLAYGROUND=true. By default Mesh uses port 60557 for GraphQL, but that can be changed with the GRAPHQL_SERVER_ADDR env var.