---
- milestones: milestones = GET /projects/:project_id/milestones?
- milestone: milestone = GET /projects/:project_id/milestones/:milestone_id
- create_milestone: POST /projects/:project_id/milestones?
- edit_milestone: PUT /projects/:project_id/milestones/:milestone_id?
- milestone_issues: issues = GET /projects/:project_id/milestones/:milestone_id/issues