changed output of avatar so that the image is now a png and not a webp

README.md

 ###### New Features
 - NSFW commands now have the same system of preventing dupe outputs
 ###### Minor Changes
+- `avatar` now outputs a png if the image is static.
 - Moved NSFW commands to use aiohttp instead of requests which hopefully will wield quicker response times.
 - Minor refactoring in places, which involves some directory movement.
 ###### Bug Fixes

Roxbot/cogs/util.py

 		if not user:
 			user = ctx.author
 
-		url = user.avatar_url
+		url = user.avatar_url_as(static_format="png")
 		if url.split(".")[-1] == "gif":
-			avaimg = 'avaimg.gif'
+			avaimg = '{0.name}.gif'.format(user)
 		else:
-			avaimg = 'avaimg.webp'
+			avaimg = '{0.name}.png'.format(user)
 
 		async with aiohttp.ClientSession() as session:
 			async with session.get(url) as img: