Add PublicBody.search

Search for public bodies whose searchable attributes are like a given
query.
Extract quarters_between to DateQuarter lib
Add rake tasks for James Cheshire stats
Remove Total Requests from quarterly stats

Was confusing what the number meant; easier to just sum numbers in the
quartery columns to get totals.
Merge branch 'issues/1390-james-cheshire-infographic' into rails-3-develop