not overwriting app config if it already exists

db/seeds/backer.rb

@@ -13,7 +13,8 @@ def create
 
   #set pod url
   username = backer_info[backer_number]['username'].gsub(/ /,'').downcase
-  set_app_config username
+  set_app_config username unless File.exists?(Rails.root.join('config', 'app_config.yml'))
+
   require File.join(File.dirname(__FILE__), "..", "..", "config", "initializers", "_load_app_config.rb")
 
   # Create seed user

db/seeds/dev.rb

@@ -15,7 +15,9 @@ def set_app_config username
 end
 
 username = "tom"
-set_app_config username
+set_app_config username unless File.exists?(Rails.root.join('config', 'app_config.yml'))
+
+require Rails.root.join('config',  "initializers", "_load_app_config.rb")
 
 # Create seed user
 user = User.build( :email => "tom@tom.joindiaspora.com",

db/seeds/tom.rb

@@ -14,7 +14,8 @@ def set_app_config username
   file.close
 end
 
-set_app_config "tom"
+set_app_config "tom" unless File.exists?(Rails.root.join('config', 'app_config.yml'))
+
 require 'config/initializers/_load_app_config.rb'
 
 # Create seed user