Adding version check to config.py as reminder for format changes

config.py.sample

 # Copy this file to config.py and fill in necessary values
 CONFIG = {
+	'__config_version': 1,
 	'client_token': 'token',
 	'command_prefix': '$rb_',
 	'kick_emoji': '👢',

rocketbot.py

 from cogs.generalcog import GeneralCog
 from cogs.joinraidcog import JoinRaidCog
 
+CURRENT_CONFIG_VERSION = 1
+if (CONFIG.get('__config_version') or 0) < CURRENT_CONFIG_VERSION:
+    raise RuntimeError('config.py format may be outdated. Review ' +
+        'config.py.sample, update the "__config_version" field to ' +
+        f'{CURRENT_CONFIG_VERSION}, and try again.')
+
 class Rocketbot(commands.Bot):
 	def __init__(self, command_prefix, **kwargs):
 		super().__init__(command_prefix, **kwargs)