rdbi: switch back to master
update date in gemspec
Makefile to build deb/rpm packages

FPM can build rpm and deb packages from our gem dependencies.
FPM should be installed with:

  gem install fpm

We collect all dependent gems with bundler:

  bundle install --without development
  bundle pack --all

The `--all` switch also puts unpacked gems in vendor/cache that were installed from git.
All generated packages are configured to install to /usr/share/libertree/gems .