Clickhouse-connect

Bug fix
* Fix 'SHOW CREATE' issue. https://github.com/ClickHouse/clickhouse-connect/issues/61

Bug fix
* "Queries" that do not return data results (like DDL and SET queries) are now automatically treated as commands. Closes https://github.com/ClickHouse/clickhouse-connect/issues/59

New Features
* A UUID session_id is now generated by default if `session_id` is not specified in `clickhouse_connect.get_client`
* Test infrastructure has been simplified and test configuration has moved from pytest options to environment files

Bug Fixes
* UInt64 types were incorrectly returned as signed Python ints even outside of Superset. This has been fixed
* Superset Engine Spec will now format (U)Int256 and (U)Int128 types as strings to avoid throwing a conversion exception

Breaking changes
* The row_binary option for ClickHouse serialization has been removed. The performance is significantly lower than Native format and maintaining the option added complexity with no corresponding benefit

Bug Fixes
* The Database Connection dialog was broken in the latest Superset development builds. This has been fixed
* IPv6 Addresses fixed for default Superset configuration

Bug Fixes
* Add single retry for HTTP RemoteDisconnected errors from the ClickHouse Server. This prevents exception spam when requests (in particular inserts) are sent at approximately the same time as the ClickHouse server closes a keep alive connection.

Bug Fixes
* Fix incorrect validation errors in the Superset connection dialog