Fixes https://github.com/divio/django-cms/issues/2487
CREATION_BY_TEMPLATE changed to CREATION_BY_CODE
Merge pull request #2487 from Chive/fix/delete-static-placeholder-plugin

Emptying a static placeholder will not be published
Merge pull request #2490 from spillevink/bugfix/creation_by_code_typo

CREATION_BY_TEMPLATE changed to CREATION_BY_CODE