Change circleci to travis

[Gianfranco97]

I'm submitting a...

• [ ] Regression (a behavior that used to work and stopped working in a new release)
• [ ] Bug report
• [x] refactoring request
• [ ] Feature request
• [ ] Documentation issue or request
• [ ] Support request => Please do not submit support request here, instead see https://github.com/glpi-project/node-module-glpi/blob/develop/CONTRIBUTING.md#questions-or-doubts

Expected behavior

Change the continuous integration service of Circleci to Travis.