Merge pull request #770 from adamarla/master

First codex
New function to list folder with codex.jpg but not codex.png
Merge pull request #771 from abhinavc/master

New commandline method - list_missing_pngs added
Merge pull request #772 from adamarla/master

Corrections to versions
[cron-git-commit] @ 14.05
Simplified, more robust logic for list_missing_pngs

For some reasons, dirname didn't work with xargs on server
when it was on local machine.
Merge pull request #773 from abhinavc/master

Robust-ified list_missing_pngs
[cron-git-commit] @ 14.17
[cron-git-commit] @ 14.24
Merge remote-tracking branch 'upstream/master'