Added album covers to the musicbrainz api

[ltctceplrm]

To complete issue #113.

I also added the missing manga media type since I couldn't get the plugin to build otherwise.

[ltctceplrm]

Ignore the part about the missing manga media type, I made a mistake there since it was already included.

[ltctceplrm]

I intended to create a new pull request to amend #106 but it seems I added it to this commit instead, I hope that's still okay.

[mProjectsCode]

Thanks for the PR. Ping me once you are done so that i can merge this. :)

[ltctceplrm]

You're welcome, I was thinking of doing #89 as well, but I have some questions about that: Both writer and director are included in OMDbapi adding the writer would be easy but the director is currently already placed under the producer field in the plugin, would it be okay if I renamed producer to director in the movies model and the OMDbapi? Director would be more correct but unfortunately MALapi doesn't give director and writer information so I'd have to add an empty string for movies grabbed with MALapi.

Would this be acceptable or should I just add writer and leave the director as producer?

An extra question is if I do change the producer field in movies, should it also be renamed in series? I can add writer and director fields for TV series as well and for anime grabbed by MALapi I can leave them empty again + rename producer to studio since it currently grabs the studio info and puts it under the producer field.

[mProjectsCode]

I would say yes, as it seems to be requested by many. And adding the same changes to series seems like a good idea, even if that will result in some empty fields.

[ltctceplrm]

There, it should be done now @mProjectsCode.

[mProjectsCode]

LGMT, will merge now and go over the code and maybe release it tomorrow

[ltctceplrm]

Awesome, thank you 😄