Add/change new bot events.
Add/change new bot events.

Custom events are now prefixed with "bot_" as to avoid collision with standard discord.py events.
Current new events: bot_on_user_ratelimit, bot_on_command, bot_on_response, bot_on_error, bot_on_discord_error, bot_on_general_error, and bot_on_ready_boot (renamed from on_ready_boot).

Also, minor update to use `bot.change_presence` instead of `bot.change_status` for v0.13.0.
jkchen2/JshBot,jkchen2/JshBot