GitLab API V4 support for composer files fetching
GitLab API V4 support for composer files fetching

Based on the composer's migration guide from V3 to V4, the blobs api is deprecated and moved to "files"

```
Moved GET /projects/:id/repository/commits/:sha/blob?file_path=:file_path and GET /projects/:id/repository/blobs/:sha?file_path=:file_path to GET /projects/:id/repository/files/:file_path/raw?ref=:sha
```
terramar-labs/packages,terramar-labs/packages