#24 OCM 0.23.12 crashes when none-jpg files in picture dir exist

[teq2]

ocm 0.23.12. crashes, if none-picture files are located in the picture dir.

OCM should ignore non picture files. I am using the geopics-script to download the spoiler images. This script stores a file "fingerprint" in the appropriate directory which ocm grabs and tries to treat as a jpg file -> crash.