Added meta information for distribution, specifying:

  - homepage, pointing to meta.cpan.org
  - repository, pointing to Github (took some time for me to locate it)
  - bugtracker, pointing to rt.cpan.org

  Homepage could be http://search.cpan.org/~lthegler/Date-Holidays-DK/
  but the tendency seem to be moving to meta over search, it could
  also just be github, but that is specified for repository so it is
  locatable (especially via meta).

  Repository, is of course Github

  Bugtracker is pointing to RT, but could also be Github, but that is
  already specifed, so RT is a good candidate, unless you want to
  change the information flow.