Add script for pattern testing basing on tavern.yaml format using test_tools.
Thanks to this messeges are more clear and requests are integrated with test_tools, so it's possible to enable schema verifcation during tests
Pattern tests no longer require tox
pytest -m api/condenser_api
pytest -m 'method/get_account_history and negative/False'
pytest -m 'method/get_account_history or method/enum_virtual_ops and api/block_api'
Compatibility with tavern is kept, so it's still possible to run tests with tox and tavern