Get merge request approvers from the API

Description

A customer is asking that we add the ability to get the list of merge request approvers from the API.

Proposal

In projects settings, list of reviewers is available on web interface. In API, this list is not available : https://gitlab.com/help/api/projects.md

Please, can you add it ?

Links / references

http://docs.gitlab.com/ee/api/projects.html