Add a None check when setting status in Client.change_status.
Add a None check when setting status in Client.change_status.

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