Merge pull request #14 from Kami/parse_metadata

Parse video and audio stream metadata and fix a bunch of broken tests
Merge pull request #15 from Kami/add_travis_config

Add travis config and modify tests so they work on Travis CI
Create multiple thumbnails in one ffmpeg call
Changable jpeg quality when creating thumbnail
Change DEFAULT_JPEG_QUALITY to 4, to have good quality with reasonable size
Merge branch 'multiple_thumbnails' into develop