Start rewriting the component based in Yum.

Start with the management of Yum repositories.
Add tests for the removal of outdated Yum repositories
Better reporting and bug fixes
Add tests for the initialize_repos_dir method
Generate repository files, together with their tests
Package Template::Toolkit files
Add support for reverse proxies in the repositories' descriptions.

Reverse proxies modify the server portion of the repository's URL, and
thus they affect how the repository files are rendered.
Tiny documentation for the repository template
Test that files are cancelled on errors
Documentation improvements
Test port number handling in reverse proxies
Add a trivial template for the versionlock configuration
Outline the Configure method
Add textual description to the first test of generate-repos
Document properly the generate-repos method
Add the skeleton for updating packages, with some helper methods.
Add a script for testing update_pkgs
More tests and documentation
Compute the list of unneeded packages only if they will be truly removed
Finish tests for update_pkgs