Keep config as Oxidized::Config instead of hash

The model will look like this:

  cmd 'show ip cef' do |out|
    out.type = 'poop'
    out
  end

  cmd 'show process cpu' do |out|
    out.type = 'poop'
    out
  end

  cmd 'show memory statistics' do |out|
    out.type = 'poop'
    out
  end

I think it's cleaner.