fix: fix PathMixin
doc: add CHANGELOG for v0.6.6
Merge branch 'hotfix/0.6.6'
Merge tag '0.6.6' into develop

Version 0.6.6
chore: remove "duplicate language" warnings
chore: add docker-friendly default values
chore: update docker image to ubuntu 14.04
doc: add CHANGELOG for v0.7
Merge branch 'release/0.7'
Merge tag '0.7' into develop

Version 0.7
fix: install vobsub2srt
doc: add CHANGELOG for v0.7.1
Merge branch 'hotfix/0.7.1'
Merge tag '0.7.1' into develop

Version 0.7.1