Added README.md
Using SemVer for version numbers
Changed interface for new()

Was:

    Deb::FileName->new('perl_5.14.2-21_amd64.deb');

Now:

    my $deb = Deb::FileName->new(
        string => 'perl_5.14.2-21_amd64.deb',
    );

This change is done to simplify future additions to this module.