WIP - Websites homepage perf

Spike on improving the performance of the index page for a particular location website. This is a subsequent topic branch off https://github.com/G5/g5-content-management-system/pull/456

https://www.pivotaltracker.com/story/show/79415538
The issue here is that slug is not actually a column on the model, otherwise I would agree with using a where statement. slug is a method that calls parameterize on the name attribute of the model, which is why I took the approach of just grabbing all the web sites and then using detect.

It might in theory be possible to monkey with the slug to reverse the parameterization and get a string that would match on the name attribute in the db, but since postgres is case sensitive on query strings and I would have no way of knowing what might be capitalized in the slug before it became a slug, I'm not confident it would work.