Change localize method API to allow grouping methods in the same parser

This way you call localize with a hash containing the :using key:

    localize :price, :total, :using => :numeric

README.md

@@ -94,7 +94,7 @@ Given a product model with a `total` method, that is a simple calculation of `qu
 ```ruby
 class Product < ActiveRecord::Base
   include I18n::Alchemy
-  localize :total => :number
+  localize :total, :using => :number
 
   def total
     quantity * price
@@ -117,7 +117,7 @@ your class have both reader and writer methods available:
 ```ruby
 class Product
   include I18n::Alchemy
-  localize :released_at => :date
+  localize :released_at, :using => :date
 
   attr_accessor :released_at
 end
@@ -160,7 +160,7 @@ If you are using `localize`, you can mix the custom parsers with your existing c
 ```ruby
 class Product < ActiveRecord::Base
   include I18n::Alchemy
-  localize :total => MyCustomNumberParser
+  localize :total, :using => MyCustomNumberParser
 end
 ```
 

lib/i18n_alchemy.rb

@@ -28,8 +28,12 @@ def localized(attributes=nil, *args)
     end
 
     module ClassMethods
-      def localize(methods_hash)
-        self.localized_methods = self.localized_methods.merge(methods_hash)
+      def localize(*methods, options)
+        parser  = options[:using]
+        methods = methods.each_with_object(localized_methods) do |method_name, hash|
+          hash[method_name] = parser
+        end
+        self.localized_methods = methods
       end
 
       def custom_parsers(parsers_hash)

test/models/product.rb

@@ -1,7 +1,8 @@
 class Product < ActiveRecord::Base
   include I18n::Alchemy
-  localize :total => :number, :estimated_delivery_at => MyCustomDateParser,
-    :estimated_last_comission_payment_at => :timestamp
+  localize :total, :using => :number
+  localize :estimated_delivery_at, :using => MyCustomDateParser
+  localize :estimated_last_comission_payment_at, :using => :timestamp
   custom_parsers :released_month => MyCustomDateParser
 
   attr_protected :my_precious

test/models/user.rb

@@ -2,5 +2,5 @@ class User
   include I18n::Alchemy
   attr_accessor :created_at
 
-  localize :created_at => I18n::Alchemy::DateParser
+  localize :created_at, :using => :date
 end