Allow nodes to skip the registry

[Tritlo]

I've added an option to nodes to skip the registry. This allows the user to control whether the node implementation of a model gets used. My use case is that I want to enable:

class PrivateProfileNode(DjangoObjectType):
  email = graphene.Field(graphene.String)
  username = graphene.Field(graphene.String)

  class Meta:
    model = Profile
    interfaces = (graphene.relay.Node,)
    skip_registry = True


class ProfileNode(DjangoObjectType):
  username = graphene.Field(graphene.String)

  class Meta:
    model = Profile
    interfaces = (graphene.relay.Node,)

without having to worry about the email leaking out via some other nodes.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling fbeea2c on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling aed7229 on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[coveralls]

Coverage increased (+0.009%) to 92.497% when pulling aed7229 on Tritlo:skip-registry into 5d6c7f2 on graphql-python:master.

[syrusakbary]

Interesting approach! Will think a little bit more about it, but I think is a good idea :)

[syrusakbary]

With the PR #115, this will be done but using skip_global_registry instead :)