Update to 0.29
    
    - New upstream release 0.29
      - Quiet compiler warning (GH#2)
      - Canonical repository moved to https://github.com/moose/Package-Stash-XS
    - Package new CONTRIBUTING file
    - Don't bother running the extra tests
    - Drop EL-5 support
      - Drop legacy Group: tag
      - Drop explicit buildroot cleaning in %install section
      - BR: perl-devel and perl(Variable::Magic) unconditionally
      - Drop workaround for building with Test::More < 0.88