Rename 'data' to 'date_attributes'

Prevents ambiguity, since there is already a `date` property defined in
the instance.

plugins/date.rb

@@ -45,10 +45,10 @@ module Octopress
     # Returns the date-specific liquid attributes
     def liquid_date_attributes
       date_format = self.site.config['date_format']
-      data = {}
-      data['date_formatted']    = format_date(self.data['date'], date_format)    if self.data.has_key?('date')
-      data['updated_formatted'] = format_date(self.data['updated'], date_format) if self.data.has_key?('updated')
-      data
+      date_attributes = {}
+      date_attributes['date_formatted']    = format_date(self.data['date'], date_format)    if self.data.has_key?('date')
+      date_attributes['updated_formatted'] = format_date(self.data['updated'], date_format) if self.data.has_key?('updated')
+      date_attributes
     end
 
   end