Removed file links, Image preview compatibility for Symphony 2.3.3

I guess this breaks 2.3.2 Compatibility?
REALLY make image previews working in 2.3.3

Dirty Hack described here:
http://www.getsymphony.com/discuss/thread/101275/2/#position-24
Merge pull request #233 from animaux/master

REALLY make image previews working in 2.3.3, plus file link removal, closes #222