Revert "FIX: fixnum type site setting can't be more than 20000"

This reverts commit 636cc66e1f8d7ff1e81641eb8f92fdb010eeb122.

lib/site_setting_extension.rb

@@ -310,8 +310,8 @@ module SiteSettingExtension
     type = get_data_type(name, defaults[name.to_sym])
 
     if type == types[:fixnum]
-      # value should be less than 20000
-      valid = false if value.to_i > 20000
+      # validate fixnum
+      valid = false unless value.to_i.is_a?(Fixnum)
     end
 
     return valid