***API for bot database ***
configuration
bot_keep_uuid : true/false (keep or delete uuid data when Skn.Bot.delete)
mix ecto.migrate -r Skn.Bot.Repo --log-sql
mix ecto.rollback -r Skn.Bot.Repo --log-sql
mix ecto.rollback -r Skn.Bot.Repo --log-sql --to 20181125012555