Add 'Ogg' as supported audio format
Merge pull request #18 from bc-petrkotek/add-ogg

Add 'Ogg' as supported audio format
Support force conversion into specified container (--mp4, --mkv)
Merge pull request #17 from bc-petrkotek/support-different-containers

Support force conversion into specified container (--mp4, --mkv)
Handle "File not found" case