request apk tzdata in alpine.Dockerfile

hi,

very thx for this application !! :)

is it possible to add pkg tzdata in alpine.Dockerfile ?

```
RUN set -eux ; \
     apk --no-cache add \
         tzdata \
         mpd \
         mpc \
```

this is for adding TZ in docker-compose like

```
    environment:
      - TZ=Europe/Paris
```

or any else TZ's location :)

Best Regards

