Cache RIT Images better

[mxmeinhold]

This is a bad cache

packet/packet/context_processors.py

Lines 58 to 70 in f61cd2b

	@lru_cache(maxsize=256)
	def get_rit_image(username: str) -> str:
	if username:
	addresses = [username + '@rit.edu', username + '@g.rit.edu']
	for addr in addresses:
	url = 'https://gravatar.com/avatar/' + hashlib.md5(addr.encode('utf8')).hexdigest() + '.jpg?d=404&s=250'
	try:
	gravatar = urllib.request.urlopen(url)
	if gravatar.getcode() == 200:
	return url
	except:
	continue
	return 'https://www.gravatar.com/avatar/freshmen?d=mp&f=y'

It caches the first call to this function for any given username (up to 256 of them) via functools.lru_cache, which is bad, because it kinda defeats the point of gravatar.

We could do some form of caching, but probably shouldn't. Loading these images lazily in the frontend would probably be much better.

At the very least, please remove the cache so we can stop kicking the pods to have photos update.