Adds instructions to README for Docker setup
Adds instructions to README for Docker setup

From my investigation using a bash session on the Dockerfile, cloudtunes-server never started with superviser because it would always fail with:

```
!!!Cannot import local settings!!!

You need to copy cloudtunes/settings/local.example.py
to cloudtunes/settings/local.py and fill in the None's.

https://github.com/jakubroztocil/cloudtunes#installation
```
danieldc/cloudtunes,Jaquesmusicplayer/MUSICA,seem-sky/cloudtunes,Jaquesmusicplayer/MUSICA,suzyelbow/cloudtunes,danieldc/cloudtunes,suzyelbow/cloudtunes,jkbrzt/cloudtunes,Jaquesmusicplayer/MUSICA,sheafferusa/cloudtunes,rschmidtz/cloudtunes,jakubroztocil/cloudtunes,fiziksis/player,jkbrzt/cloudtunes,suzyelbow/cloudtunes,rschmidtz/cloudtunes,jakubroztocil/cloudtunes,saitodisse/cloudtunes,sheafferusa/cloudtunes,danieldc/cloudtunes,sheafferusa/cloudtunes,seem-sky/cloudtunes,rschmidtz/cloudtunes,saitodisse/cloudtunes,jakubroztocil/cloudtunes,saitodisse/cloudtunes,jkbrzt/cloudtunes,fiziksis/player