Support for custom tables names

Currently, the history table name is hardcoded (APP_historicalMODEL).
This pull request add support for custom tables names by adding a
`db_history_table` option.

As Django reject all unknown option in `Meta` inner class, I've added an
`History` inner class to store this option (and possibly others future
options).

```
class Organization(models.Model):
    name    = models.CharField(_('Organization or Name'), max_length=25)
    address = models.CharField(_('Address'), max_length=250)
    zipcode = models.CharField(_('Postal code'), max_length=10, null=True)
    city    = models.CharField(_('City'), max_length=50)
    country = models.CharField(_('Country'), max_length=2, \
                choices=COUNTRIES_CHOICES)

    def __str__(self):
        return self.name

    class History:
        db_history_table = 'organizations_history'

    class Meta:
        db_table = 'organizations'
```

TODO: Documentation.

Author: jleroy

simple_history/models.py

@@ -117,6 +117,9 @@ def create_history_model(self, model):
         attrs.update(self.get_extra_fields(model, fields))
         # type in python2 wants str as a first argument
         attrs.update(Meta=type(str('Meta'), (), self.get_meta_options(model)))
+        history_options = self.get_history_options(model)
+        if 'db_history_table' in history_options:
+            attrs['Meta'].db_table = history_options['db_history_table']
         name = 'Historical%s' % model._meta.object_name
         registered_models[model._meta.db_table] = model
         return python_2_unicode_compatible(
@@ -225,6 +228,27 @@ def get_meta_options(self, model):
         meta_fields['verbose_name'] = name
         return meta_fields
 
+    def get_history_options(self, model):
+        """
+        Returns a dictionary of options set to the History inner
+        class of the historical record model.
+        """
+        VALID_OPTIONS = ['db_history_table']
+        if hasattr(model, 'History'):
+            history_options = model.History.__dict__.copy()
+            for key in model.History.__dict__:
+                # Ignore any private attributes that we doesn't care about, like
+                # "__module__" or "__dict__".
+                # NOTE: We can't modify a dictionary's contents while looping
+                # over it, so we loop over the *original* dictionary instead.
+                if key.startswith('_'):
+                    del history_options[key]
+            for option in history_options:
+                if not option in VALID_OPTIONS:
+                    raise TypeError("'class History' got invalid attribute: %s" % (option,))
+            return history_options
+        return {}
+
     def post_save(self, instance, created, **kwargs):
         if not created and hasattr(instance, 'skip_history_when_saving'):
             return

simple_history/tests/models.py

@@ -264,3 +264,11 @@ class Province(models.Model):
 class City(models.Model):
     country = models.ForeignKey(Country, db_column='countryCode')
     history = HistoricalRecords()
+
+class Contact(models.Model):
+    name = models.CharField(max_length=30)
+    email = models.EmailField(max_length=255, unique=True)
+    history = HistoricalRecords()
+
+    class History:
+        db_history_table = 'contacts_history'

simple_history/tests/tests/test_models.py

@@ -19,7 +19,7 @@
     ExternalModel1, ExternalModel3, UnicodeVerboseName, HistoricalChoice,
     HistoricalState, HistoricalCustomFKError, Series, SeriesWork, PollInfo,
     UserAccessorDefault, UserAccessorOverride, Employee, Country, Province,
-    City
+    City, Contact
 )
 from ..external.models import ExternalModel2, ExternalModel4
 
@@ -745,3 +745,10 @@ def test_restore_employee(self):
         self.assertEqual(original.manager_id, 1)
         with self.assertRaises(Employee.DoesNotExist):
             original.manager
+
+class CustomTableNameTest(TestCase):
+    def get_table_name(self, manager):
+        return manager.model._meta.db_table
+    
+    def test_custom_table_name(self):
+        self.assertEqual(self.get_table_name(Contact.history), 'contacts_history')