Show progress throughout a year

[dnlgrv]

Once #6 has been completed we will have access to the gem user's AOC session. This opens up the possibility to inspect current progress throughout their AOC journey.

• Display progress through a particular year (total number of stars or per-day breakdown)
• Display progress through all years (total number of stars)

[dnlgrv]

I'm hoping that rails/thor#801 gets merged as it'll make interacting with the API a bit more natural (and thor-like) for this kind of problem.