Add different report pages

- The default /report endpoint gives the leaderboard for the current week
- /report/<year> gives the leaderboard for that year
- /report/<year>/<month> gives the leaderboard for that month
- /report/<year>/<month>/day gives the leaderboard for that day
- /report/<year>/week/<week_number> gives the leaderboard for that week
Fix the "day" report.
Change up presentation for the reports.
Remove unnecessary leaderboard queries.
Update a comment.
Re-work from scratch the way we get the date from a year and a week number
Merge branch 'feature/reports' of github.com:fedora-infra/tahrir into feature/reports
Enhance report description.
Link to reports from the explore page.
Typofix.
Add a space there to match the other code

Just a typofix, what it says on the can :)
More rank information in the report(s).
Merge pull request #233 from fedora-infra/feature/reports

Add different report pages