Make fields on model have defaults value

Like who cares for their default value
Added little docstring on tests
Addes test_field_for_fk_none_on_creation() test
Added test_field_for_fk_not_none_after_creation

So I want to create new `Continent` for my new shiny funky punky ass
        `Planet` that I've just created, It's easy, just retrieving new
        planet from database to make `ek` available for it, Then it will
be
        fucking freaking ok to assign the fresh `Planet` to
        our sucker `Continent`.
Added Helper model

base64 encoded value won't be available at first time creation.
It can ve accessible by getting the object from database after creation
when it get saved completely, But what if we don't want to get our
base64
key from our sweet model by retrieving it again from database?

It's easy, efficient, holly and molly!
Should be run anyway
Added test_field_with_property_defined
Added python 3.3 to be tested
renamed, because there is no property defined here!
self.assertNotEquals is deprecated
Added more comments and some more tests
Updated ChangeLog.rst
Merge pull request #6 from Alir3z4/task-#3-more-tests

Fixes #3 more tests