New REST API provider

[s-kostyuk]

Rewritten an REST API implementation. The following changes was made:

• a single REST API handler was split into several new entities (aiohttp Applications) by resources they control;
• abandoned an idea to declare request handlers as class methods;
• moved all dependencies to aiohttp Application's data storage;
• created builders for aiohttp Applications;
• refactored restricted_access_decorator and json_decode_decorator;
• performed a migration to the new REST API implementation in Controller.

This request closes #40 and unblocks #41.

[s-kostyuk]

Three follow-up commits was made to fix introduced bugs and a lack of some features:

• 9b69fe9 - FIX: Fixed a type of auth_service argument in RestApiProvider constructor
• 96e3cf9 - FIX: Allowed to pass a new custom event loop for RestApiProvider
• d0f859b - FIX: Fixed a signature of root_get_handler in rest_api_provider module