deprecated CircleCI

CircleCI is a hosted continuous integration and delivery system.

To integrate the GitHub Repository with CircleCI, the following steps are executed.

We add the circle.yml (deprecated for CircleCI 1.0) or .circleci/config.yml(for CircleCI 2.0) configuration file to the repository.
In CircleCI, we add the project.

Make sure the repo includes the configuration file before connecting it to CircleCI since the service will build `master` right after the connection is established.