(Sysadmin): Add guild and user blacklist.

v2 -> v3 data migration for the blacklist tables.
Added blacklists and blacklist commands
Added bot admin level to help groups.

bot/modules/reminders/reminder.py

@@ -134,6 +134,10 @@ class Reminder:
         """
         Execute the reminder.
         """
+        if self.data.userid in client.objects['blacklisted_users']:
+            self.delete(self.reminderid)
+            return
+
         # Build the message embed
         embed = discord.Embed(
             title="You asked me to remind you!",