To change a field name in django 1.7+

1.  Edit the field name in the model (but remember the old field name: you need it for step 3!)
2.  Create an empty migration
$ python manage.py makemigrations --empty myApp
3.  Edit the empty migration (it's in the migrations folder in your app folder, and will be the most recent migration) by adding

migrations.RenameField('MyModel', 'old_field_name', 'new_field_name'),

to the operations list.

4.  Apply the migration
$ python manage.py migrate myApp