Remove Markdown from bot logging
Remove Markdown from bot logging

It is easy to encode Markdown messages wrongly when composing the message dynamically. Markdown is turned off when sending error/warning logs to the group debug chat.
CodeMOOC/TreasureHuntBot,CodeMOOC/TreasureHuntBot,CodeMOOC/TreasureHuntBot,CodeMOOC/TreasureHuntBot