Allow installation from GitHub/BitBucket tarballs

The contents of downloaded tarballs (especially from GitHub/BitBucket) may not follow the default `"#{base_name}/#{version}"` schema. That's why e.g. the http://community.opscode.com/cookbooks/install_from cookbook runs `tar xvzf tarball` with `--strip-components=1 -C my_own_dir_name` options to ensure consistent results.