Allow youtube-dl.conf from user

[DanWillman]

Currently, the app is defaulting to 'merge-output-format': 'mp4'. It'd be really nice to have this be overrideable in the config, as well as possibly exposing other options, like post processing.

This would allow the client to specify other merge output formats (see here) such as MKV. Post-processing options would also be nice to be able to pass in to do things like recode/etc on complete.

If this is something you're interested in, but don't have time, I could open a Pull Request.

[DanWillman]

On second thought, maybe it would just be best with the youtube-dl.conf file. In that case, it may be best to specify that the conf is set, then pass either --config-location as an option, or the existing array of options.

This would allow for a lot more flexibility and not require a multitude of changes, and solves proxy issues as well. Currently I've made a global conf in /etc/ for the container, but that's not ideal as it'll be destroyed soon enough.