FIXED MAGE-3695: Database Media Storage doesn't export empty files to filesystem

right branch for this: https://github.com/magento/bugathon_march_2013/commit/3d6614295e259fe359eec83a61a43bd198128075

FIXES #121
Merge pull request #211 from magento/schrank-121

FIXED MAGE-3695: Database Media Storage doesn't export empty files to fi...