Added "pre_cache" field to photo sizes. 
Added "pre_cache" field to photo sizes. 

git-svn-id: 7cd57066f4757936737e83af525e37846a788f28@134 2d8b3452-2338-0410-8a60-9550768eb463

petry/django-photologue-old,seedwithroot/django-photologue-clone,jlemaes/django-photologue,seedwithroot/django-photologue-clone,rmaceissoft/django-photologue,MathieuDuponchelle/my_patched_photologue,MathieuDuponchelle/my_patched_photologue,rmaceissoft/django-photologue,RossLYoung/django-photologue,RossLYoung/django-photologue,georgemarshall/django-photologue,jlemaes/django-photologue,jlemaes/django-photologue,RossLYoung/django-photologue,rmaceissoft/django-photologue