Enhancement - Add button to delete created rooms

[cruizba]

Enhancement - Add button to delete created rooms

Deployment info

OpenVidu Teaching version: master - 11459a6
Docker Image: openvidu/openviduteaching:1.3.0-beta1
We've built or own docker image by executing ./create_image.sh in https://github.com/codeurjc-students/2019-OpenViduTeaching/tree/master/docker in order to update OpenVidu Client version to 2.15.0.

Issue description:

After create rooms from openvidu teaching via browser, is not possible to delete those created rooms.