Switch DB from sqlite to Postgres

-Postgres for production
-Migrations don't translate well between sqlite and postgres, better to just develop using the same database as production.
-Fixed migrations to work with Postgres
-Updated Readme for PG install instructions
-database config moved to .example

db/migrate/20130419010051_add_ends_to_user_roles.rb

@@ -2,6 +2,5 @@ class AddEndsToUserRoles < ActiveRecord::Migration
   def change
     add_column(:user_roles, :ends, :timestamp)
     add_column(:user_roles, :user_id, :integer)
-    remove_column(:users, :role_id)
   end
 end

db/migrate/20130423231937_alter_user_roles.rb

@@ -1,9 +1,23 @@
 class AlterUserRoles < ActiveRecord::Migration
-  def change
+  def up
     rename_table :user_roles, :user_role_joins
     change_table :user_role_joins do |t|
       t.rename :role, :role_id
-      t.change :role_id, :integer
+      #t.change :role_id, :integer
+    end
+    #for Postgres
+    connection.execute(%q{
+      alter table user_role_joins
+      alter column role_id
+      type integer using cast(role_id as integer)
+    })
+  end
+
+  def down
+    rename_table :user_role_joins, :user_roles
+    change_table :user_role_joins do |t|
+      t.rename :role_id, :role
+      t.change :role_id, :string
     end
   end
 end

db/migrate/20130614003934_remove_nickname.rb

@@ -1,5 +1,5 @@
 class RemoveNickname < ActiveRecord::Migration
   def change
-    remove_column :users, :nickname, :string
+    remove_column :users, :nickname
   end
 end