GIN index uses to find posts by tag

-remove hive_post_tags table -extend hive_posts for a column with an arrays of tags id -tags are added next after a post, not in paralles as it was previously -fix bug with not removing tags for a post whose author removed tags during edition

hive/db/sql_scripts/upgrade/upgrade_table_schema.sql

@@ -407,3 +407,5 @@ CREATE INDEX IF NOT EXISTS hive_posts_promoted_id_idx ON hive_posts (promoted, i
 
 
  CREATE INDEX IF NOT EXISTS hive_posts_tags_ids_idx ON hive_posts USING gin(tags_ids gin__int_ops);
+
+ DROP TABLE IF EXISTS hive_post_tags;