Add a page with experimental statistics on public bodies

The statistics on the status of the requests to a particular
public body are too slow to calculate on-the-fly, so this
commit adds:

 * Extra columns on public_bodies to store counts of
   the successful, not held, and overdue request counts
   for each public body.

 * A rake task which should be run periodically to update
   the overdue request count column.

If Javascript is not available, the summary statistics are
shown as tables.  If Javascript is available, graphs are
drawn with Flot.

0 files changed, 0 insertions, 0 deletions