Sort displayed addons (bnc#888567)

- **Not finished yet**
- Needs SCC/Connect support
I think it need not to be public....I think there need to be only two methods ( even one will be fine, but for caching it is better to have two )
```
class AddonSorter
  attr_reader :sorted_addons
  
  def initialize(addons)
   @sorted_addons = sort(addons)
  end

private
```