Support raw GraphQL Mutation

[sibelius]

Example of raw graphql mutation based on https://learngraphql.com/basics/defining-mutations/2

const Mutation = new GraphQLObjectType({
  name: "BlogMutations",
  description: "Mutations of our blog",
  fields: () => ({
    createPost: {
      type: Post,
      args: {
        title: {type: new GraphQLNonNull(GraphQLString)},
        content: {type: new GraphQLNonNull(GraphQLString)}
      },
      resolve: function(source, args) {
        let post = Object.assign({}, args);
        // Generate the _id
        post._id = `${Date.now()}::${Math.ceil(Math.random() * 9999999)}`;
        // Assign a user
        post.author = "arunoda";

        // Add the Post to the data store
        PostsList.push(post);

        // return the new post.
        return post;
      }
    }
  })
});

I think this could work on apollo as well

[lucasbento]

Related to #1.