Multiline inserts, fix memory leak caused by query_id, fix stack trace when no live server

feature: support for multiline inserts (some CH drivers are sending FORMAT TabSeparated with multiple rows e.g. Java ExecuteBatch) so we have count number of rows in data
improvement: log in µs & log only insert statements - SELECTs are not that interesting and actual query isn't logged at all
improvement: enable debug with ENV var
fix: memory leak caused by query_id in query params - basicaly every query is unique -> new map[]Table for every query with query_id -> tables were never deleted. I have added two options: clean_interval - all tables which are not updated for clean_interval will be deleted; remove_query_id - will remove query_id=... from query params before create / insert to Table (in our load the mem usage was 800MB+ within ~3h, with remove_query_id is the mem usage stable ~45MB) this can probably solve #23
fix: return 503 instead of stack trace when there is no live clickhouse endpoint

nikepan / clickhouse-bulk