list_cards() should be able to populate checklists and comments (actions) in a single request

[gdietz]

Currently, comments and checklists are populated lazily for each card as they are requested, generating a new request for each card+checklist or card+comments. When dealing with a lot of cards, we could easily exceed Trello's rate limits. However, the trello api allows you to specify actions and checklists as nested query params when fetching a list of cards. Thus, we should be able to populate a list of cards and optionally include their actions, comments, and checklists in a single request.