Redo mac bans - reduce amount of db queries on login

Works just like ip and hwid bans in that they are loaded on startup

src/main/resources/db/migration/postgresql/V0.10__ban.sql

@@ -15,3 +15,12 @@ CREATE TABLE hwid_ban
     PRIMARY KEY (hwid)
 );
 GRANT SELECT ON TABLE hwid_ban TO ${server-username};
+
+CREATE TABLE mac_ban
+(
+    mac varchar(30) NOT NULL,
+account_id integer,
+    created_at timestamp DEFAULT now() NOT NULL,
+    PRIMARY KEY (mac)
+);
+GRANT SELECT, INSERT ON TABLE mac_ban TO ${server-username};