no access image shown for file which ACL allows read

[kript]

Version - 2.3.0-RELEASE

I suspect this is a file rendering bug (related to #139 ) but when we click preview on a file (XML in this case) where the ACL allows the logged in use to read the file, the image thumbnail is of the 'access denied' image.

[trel]

this may be remedied since 3.0.0 now that there is no local database