Redo ip bans - reduce amount of db queries on login

Works by loading all ip bans on startup and querying the collection in memory
rather than making calls on every login.

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

@@ -0,0 +1,8 @@
+CREATE TABLE ip_ban
+(
+    ip         varchar(15)             NOT NULL,
+    account_id integer,
+    created_at timestamp DEFAULT now() NOT NULL,
+    PRIMARY KEY (ip)
+);
+GRANT SELECT, INSERT ON TABLE ip_ban TO ${server-username};