feat(GraphQL): Re-export graphql library
feat(GraphQL): Re-export graphql library

This is made for graphql-compose-* plugins: they should import `graphql`
from graphql-compose for avoiding instalation of different graphql-js
packages, also it solves linking problems in development.

Example of importing GraphQL modules (- before, + after):
```diff
- import { GraphQLInt, GraphQLNonNull } from 'graphql';

+ import { graphql } from 'graphql-compose';
+ const { GraphQLInt, GraphQLNonNull } = graphql;
```

nodkz/graphql-compose