make the relay framework work + example

[mjarkk]

There seems to be a lot of small things we need to improve to make relay work, lets track them here.

• Schema definition returns duplicated directives
• get-graphql-schema http://127.0.0.1:3000/graphql
  • fix Error: [] prisma-labs/get-graphql-schema#32
  • do not return __schema and __type in Query
• Label methods to have an ID response, required for the relay node
• Relay example examples: add Relay #7
• Graphql Input types
  • ID type never required 820b988
  • Ptr value set if input field is provided but no value set (also for variables and default variables) 4e3e0fb
  • Check behaviour on input object with pointers inside (also on variables) 5e7cd72