Add pure javascript test for /users endpoint

[mauriciovieira]

Description:

Currently, we don't have automated tests for our REST API.

To visualize our swagger file,

1. open http://petstore.swagger.io/
2. insert https://apinf.io/rest/v1/swagger.json

We should have pure javascript tests running on continuous integration similarly to apinf-fiware package (travis build), that means, no chimp.js or robot tests for it.

User Story:

• As an APInf Platform developer,
• I need Platform /users endpoint automated tested running on travis-ci
• So that it's good.

[Nazarah]

related to #2862