Write "Using Nesta with Rails" recipe

[gma]

Nesta has the potential to make attaching a sales/marketing site or blog to a Rails app incredibly easy, but it isn't currently a perfectly smooth process. We need to work out the best way to do it (in a manner that shares view templates and layouts between Rails and Sinatra) and write it up.

[gma]

The code for this has been implemented in the nesta-rails gem.