Revert login_database parameter

ansible was upgraded to 2.2.0.0 version on master branch. login_database parameter is now supported

playbooks/roles/mongo_3_0/tasks/main.yml

@@ -322,6 +322,7 @@
 - name: create mongodb users in a replica set
   mongodb_user:
     database: "{{ item.database }}"
+    login_database: 'admin'
     login_user: "{{ MONGO_ADMIN_USER }}"
     login_password: "{{ MONGO_ADMIN_PASSWORD }}"
     name: "{{ item.user }}"