Refs #3929 Forum; added migration for naaya.content.talkback attachment in comments; added method 'write_data' for NyBlobFile

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.bfile@21182 a0171fae-0946-0410-966d-b1775066cd26
Update CHANGELOG

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.bfile@21185 a0171fae-0946-0410-966d-b1775066cd26