Wrong API call on releases page

On gitlab-org/gitlab-ce!23796 we implemented the frontend for releases api.

There 3 problems:

1. it uses the wrong API URL
2. it uses undefined as the project id
3. After fixing 1 and 2, it doesn't show the author

it fetches http://localhost:3000/api/v4/project/undefined/releases instead of http://localhost:3000/api/v4/projects/:project_id:/releases (projects)