fix some problems defined it pull request comments

README.rst

@@ -84,10 +84,12 @@ Lets say we have a model called ``Fruit``:
 
     class Fruit(TranslationModel):
         name = CharField(max_length=255)
-        translatable_fields = ['name']
 
         def __str__(self):
             return self.name
+      
+        class Meta:
+            translatable_fields = ('name',)
 
 ``TranslationModel`` adds a jsonb field to this table and sets
 translations in a notation like the one below:

nece/models.py

@@ -4,7 +4,7 @@
 from distutils.version import StrictVersion
 from django import get_version
 from django.db import models
-import django.db.models.options as options
+from django.db.models import options
 from nece.managers import TranslationManager, TranslationMixin
 from nece.exceptions import NonTranslatableFieldError
 
@@ -13,7 +13,7 @@
 else:
     from nece.fields.pgjson import JSONField
 
-options.DEFAULT_NAMES = options.DEFAULT_NAMES + ('translatable_fields',)
+options.DEFAULT_NAMES += ('translatable_fields',)
 
 
 class TranslationModel(models.Model, TranslationMixin):

tests/models.py

@@ -10,7 +10,7 @@ class Fruit(TranslationModel):
     scientific_name = models.CharField(max_length=255)
 
     class Meta:
-        translatable_fields = ['name', 'benefits']
+        translatable_fields = ('name', 'benefits', )
 
     def __str__(self):
         return self.name