Message.author is now either Member or User.
Message.author is now either Member or User.

Closes #11.

khazhyk/discord.py,rapptz/discord.py,eartsar/discord.py,Theoretical/UselessBot,Harmon758/discord.py,Harmon758/discord.py,Rapptz/discord.py,jhgg/discord.py,lgkern/PriestPy,imayhaveborkedit/discord.py,mgardne8/discord.py,variablehair/Eggplantato,megamit/discord.py