Added i18n keys for some of the validations.

inclusion_of needs some additions in mattmatt-validatable before it can parameterize the i18n message.

lib/simply_stored/couch/validations.rb

@@ -34,6 +34,10 @@ def valid?(instance)
         def message(instance)
           super || "is invalid"
         end
+
+        def i18n
+          super || "#{i18n_prefix}.invalid"
+        end
       end
 
       class ValidatesUniquenessOf < ::Validatable::ValidationBase
@@ -50,6 +54,10 @@ def valid?(instance)
         def message(instance)
           super || "#{attribute.to_s.try(:humanize) || attribute.to_s} is already taken"
         end
+
+        def i18n
+          super || "#{i18n_prefix}.not_unique"
+        end
       end
 
       def validates_inclusion_of(*args)