Add a ban.ip_manager mongo service

 public function findById($ban_id) {
+    $result = $this->mongo->get('ban_ip')
+      ->findOne(array('iid' => $ban_id), array('ip'));
+    return $result ? $result['ip'] : FALSE;
+  }

When we ban an IP in mongo we never set iid, as a result it won't exist, instead we will have an _id. This will be a mongo_id object based _id. I am thinking that we need to swap this query to use _id (free index) and also explicitly set the _id when we create the ban record.

Although there was no move in 4 years on that issue, the feature and its implementation might make sense in 8.x-2.x, so bumping.

Rebased on 8.x-2.x but needs changes to use the 8.x-2.x API instead of 8.x-1.x.

PR at https://github.com/fgm/mongodb/pull/63