Auto update bot

From version 2.2.0+ bot able to update itself

When you see the message:

** UPDATE NOTICE ** Please run file update-bot.bat to update bot to the latest released version X.Y.Z

Please close the bot and run the file update-bot.bat so the bot can update itself to the latest version (bot already downloaded new version and unzip/extract before displaying the above message)

If you run the script and get an error message, please go to our Release page and update the latest version manually

This feature auto-update can be disabled by providing the following key to user-config.properties file:

disable.auto-update=true

FYI: upon bot starting, there is 33% chance for the bot to check for new released version and do auto-update