handle Game.name being None
handle Game.name being None

re #221, Game.name can still be None, which will cause TypeError on
str(game).

Currently discord does not treat these weird statuses uniformly, with it
showing as playing a game on mobile, but not playing a game on desktop. It
may be useful to know users are in this weird state.

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