Refacto/uniformisation & correction

like that ?

```ruby
package 'git' do
  action :install
  only_if do
    install_git = false
    node[:'bi-joe'].each do |key, data|
      if data.has_key?(:install_method)
        install_git = true if data[:install_method] == 'git'
        break if install_git
      end
    end
    install_git
  end
end
```