[1.4.x] Bumped release date for 1.5.5 & 1.4.9.
[1.4.x] Bumped release date for 1.5.5 & 1.4.9.

Backport of 4ce5c119b5 from master

riklaunim/django-custom-multisite,riklaunim/django-custom-multisite,riklaunim/django-custom-multisite