Retrieve all the files of a package
Retrieve all the files of package matching the pattern
Replace tar_file with tarball
Replace tar_file with tarball
Enable get_all_packages function to filter packages by their extension
Create the `packages` table storing the package name and link them to the `files` table
Add SQL script create the link between the packages and the files tables
Fix the foreign key reference to point to the table rather than the object

Thanks @puiterwijk for finding it out
Add an intermediary table between Package and File which lists the Releases

With this scheme we are going from
  Package -> File
to
  Package -> Release -> File

Which is a good enhancement from a DB scheme pov