Replace RAILS_ROOT with Rails.root for Rails 3
Replace Dispatcher.to_prepare with Rails.configuration.to_prepare
Fix the "can't modify frozen array" error with Rails 3
Rename the .rhtml files to .html.erb for Rails 3
Update the routing for Rails 3
Explicitly add a survey method to UserController

Previously the survey.rhtml method was rendered by default
if no action matching 'survey' was found in the controller,
but this doesn't seem to be the case with some configurations.
This is rather unsatisfactory, in that we haven't found
documentation of any change that might cause this different
behaviour, but the pragmatic solution is to just to add
the empty survey method and move on.
Since mailer views are plain text, they should be text.erb

Thanks to Henare Degan for pointing this out in his theme upgrade
document.
Configuration is now AlaveteliConfiguration
Merge remote-tracking branch 'mysociety_github/rails-3' into rails-3
Merge branch 'rails-3'