Upgrade aiohttp requirement to 2.0.
Upgrade aiohttp requirement to 2.0.

Apparently this doesn't cause any issues with the existing code as-is.
I suspect the real issue will be with people's third party code.

Harmon758/discord.py,imayhaveborkedit/discord.py,mgardne8/discord.py,Rapptz/discord.py,khazhyk/discord.py,Harmon758/discord.py,rapptz/discord.py