new stable release
- cleanup and refactoring
- change order of discovery for configuration file, local process-media.yaml is now read before any /etc/process-media.yaml
- allow to specify a strip_exclude for video (only support gps tag for now), close #9
- add new option strip_exclude in format definition and do some cleanup and refactoring
- add ffmpeg git version 20160928
- no longer need dependency on ffmpeg