Harmonize and sync Postman collections

[mgonzalezlopezudc]

First of all, @jason-fox thanks a mill for your fantastic job at maintaining the FIWARE Tutorials repos.

I have found that there are three different versions for the Postman collection of each tutorial:

• The .postman_collection.json file in the GitHub repo
• The one included in the Postman FIWARE Foundation eV Public Workspace
• The one pointed by the Run in Postman button in the README.md file of the tutorial

They are not always the same and sometimes they contain different kind of errors. It would be very helpful to keep them in sync.

Also, whenever someone fixes an error, how do you prefer to get notified via a pull request: in GitHub or Postman?