Add unique ID for each context

src/main/java/me/bobert/netneutrality/context/MessageCommandContext.java

@@ -43,6 +43,15 @@ public class MessageCommandContext extends CommandContext {
         return event;
     }
 
+    @Override
+    public String getId() {
+        return String.format("%s:%s:%s:%s",
+                getGuild() == null ? "PrivateMessage" : getGuild().getId(),
+                getChannel().getId(),
+                getDiscordUser().getId(),
+                message.getId());
+    }
+
     @Override
     public ChannelType getType() {
         return event.getChannelType();