+ fixed issue with registry matching in DockerConfig.get_basic_token

Related to #166

+ added setting INSECURE_REGISTRIES
+ added ssl flag to aiohttp in check_actions_util

Closes #111

+ renamed variable
+ removed DOCKER_HOST and DOCKER_CONFIG from agents config.py coz these variables are captured by docker cli automatically

+ apply basic token to auth request or as fallback
+ added ssl flag to other requests
+ added fallback to http scheme

Related to #111
Related to #166

+ refactor agent client error handling in _request

Closes #138

+ preserve one aiohttp session per agent client (not session per request)
+ shutdown logic (remove all clients)
+ better logging
+ better errors to frontend
+ AgentClient with async context manager

Closes #115

+ added agent common/version api
+ added AgentClientCommon class to agent_client
+ added check of version in get_container_net_kwargs (clear mac if <1.44)

Closes #163