Bot.unload_extension: don't remove commands from no module
Bot.unload_extension: don't remove commands from no module

Fixes unload_extension in the case of a command added via eval
Harmon758/discord.py,rapptz/discord.py,Harmon758/discord.py,imayhaveborkedit/discord.py,Rapptz/discord.py,khazhyk/discord.py