New board: top day, week, month, etc

[book]

I'm now working on a once_a_bins table that stores the number of releases each author made in every bin. (The bins are an idea I stole from cpan-regulars). The code supports incremental updates, so only the data about new releases is needed between each run.

This means we can work on the bins directly to produce several new boards. Some examples:

• the top 10 weekly authors:

  sqlite> select * from once_a_bins where bin like "W%" order by count desc, bin desc limit 10;
  W2014-32|INGY|351
  W2014-31|INGY|129
  W2008-02|PERFSONAR|104
  W2013-36|SHARYANTO|93
  W2014-04|SHLOMIF|90
  W2010-47|DPCHRIST|88
  W2014-03|ETHER|85
  W2010-12|MARCEL|81
  W2014-29|SHARYANTO|78
  W2012-32|SHARYANTO|75

• the top ten days:

  sqlite> select bin, sum(count) as total from once_a_bins where bin like "D%" group by bin order by total desc, bin desc limit 10;
  D2014-08-16|775
  D2012-06-13|150
  D2014-08-05|131
  D2014-08-04|129
  D2014-07-28|124
  D2011-10-28|124
  D2013-06-07|123
  D2014-07-30|122
  D2008-01-16|121
  D2014-01-21|119

• top ten releasers overall:

  sqlite> select author, sum(count) as total from once_a_bins where bin like "M%" group by author order by total desc, author desc limit 10;
  SHARYANTO|3345
  RJBS|2742
  BINGOS|2402
  ADAMK|2312
  TOKUHIROM|2008
  INGY|1878
  DROLSKY|1729
  MIYAGAWA|1686
  TOBYINK|1548
  DAGOLDEN|1444

[book]

To avoid the bad side effects of author-related boards, I'll only focus on the CPAN-wide boards: top x days of releases, etc.

[book]

The top boards have been developed on the top branch, which was merged in 396f475feb788ea3c041c0fcd806ae09378d58fd.