Move getting similar requests to the InfoRequest model.
Cache the similar requests for 1 day
Move getting popular bodies into a model method.
Use built-in SQL quoting.
Move getting recent requests into a helper method.
Restore caching for five minutes to frontpage.
Add a rake task to analyse the distribution of hits to requests.

Also removes old temp tasks.
Set cache store to memcached, turn off rack-cache.

The rack-cache gem version used by Rails (and turned on by default in
3.1) has a bug using memcached backend and the backend is unavailable.
Note that we could just add the git version with the relevant pull
request merged to the Gemfile if we wanted to keep rake-cache on, but it
seems like Varnish should really be doing the job of whole page caching
better for us.
Make fragment caching dependent on a config variable.