Checklist for releasing v0.2.0 of ammg:
x Support m4a files.
x Check for file before adding metadata to it (if opus/m4a).
x Fix cover_info being passed empty to embed metadata.

Checklist for releasing v0.2.1 of ammg:
x Fix TypeError in mutagen.File().
x Colorful print screen text.
x Fix -t not working.
x Create album in after saving metadata.
x Implement -v/--version.
