Add referrer to impression model.

remove unused features dir.

lib/generators/impressionist/templates/create_impressions_table.rb

@@ -11,6 +11,7 @@ class CreateImpressionsTable < ActiveRecord::Migration
       t.string :session_hash
       t.string :ip_address
       t.string :message
+      t.string :referrer
       t.timestamps
     end
     add_index :impressions, [:impressionable_type, :impressionable_id, :request_hash], :name => "poly_request_index", :unique => false