Add new request class

DEV_config.json

jussi/errors.py

jussi/handlers.py

jussi/httprequest.py

jussi/middlewares/__init__.py

jussi/middlewares/caching.py

jussi/middlewares/jsonrpc.py

jussi/middlewares/jussi.py

jussi/middlewares/limits.py

jussi/middlewares/update_block_num.py

jussi/request.py

jussi/serve.py

jussi/typedefs.py

jussi/upstream.py

jussi/urn.py

jussi/validators.py

jussi/ws/pool.py

tests/conftest.py

tests/test_cache_backends.py

tests/test_cache_group.py