Code review comment for lp:~gary-lasker/software-center/recommendations-categories-view

Thanks for this merge proposal! It looks good overall but I have some comments:

RecommendationsPanelCategory() duplicated quite a bit of code from RecommendationsPanelLobby,
- _update_recommended_for_you_in_cat_content looks almost identical to _update_recommended_for_you_content
- same for _on_recommended_for_you_in_cat_agent_refresh/_on_recommended_for_you_agent_refresh

I think we should simply make a single RecommendationsPanelCategory where category can be None and a option
to show the opt-in button or not (unless I overlook something but it seems they are pretty identical).