Graphql-query

- Removed GraphQL validation from types.
- Removed `graphql-core` from requirements.

Some updates:

- code stabilization;
- updated docs;
- updated build;

Added

- [PR-10](https://github.com/denisart/graphql-query/issues/10): Added new supported types to `Argument.value` (`int`, `List[str]`, `List[int]`);

Fixed

- [PR-8](https://github.com/denisart/graphql-query/issues/8): Fixed rendering a query with empty field list;

New

Add arguments as list of objects. Usage example: https://denisart.github.io/graphql-query/usage.html#argument-as-list-of-objects

First release of graphql-query
See https://denisart.github.io/graphql-query/