Import messages by newcomers on gitter

We can import data from [Gitter Developer API](https://developer.gitter.im/docs/welcome) which can be useful in creating metrics for [Newcomer metrics and gamification](http://projects.coala.io/#/projects?project=newcomer_metrics_and_gamification&lang=en) project.

Start with the Gitter Developer API documentation and the linked newcomer metrics and gamification project. Define which newcomer messages and metrics are required, then locate the community site's import and data-model entry points; done means the required Gitter data is imported in a repeatable way and is available for those metrics.

Written by the indexing model from the issue text.