Add proper support for having multiple components

[pazdera]

If the repo has more than one component configured, there should be a switch on dr add to assign it to a specific component:

dr add --git <...> --component drivers

What needs to be done

1. Add the options to configure components to the repo setup procedure.
2. Add the --component option to the dr add subcommand (link).
3. Extend the setup of the GitPackage and DebPackage classes to handle components when being added to the repository.
4. Add component to the different places where packages are listed (the List class).