- use official v0.3.13 docker images hosted on GitHub
- load configs for Element-Call (public/config.json), nginx and SSL
certs through ConfigMaps / PersistentVolumeClaims
The other options are things people usually won't need or want to
set, so just keep it to the basics.
* Rename config sample to match element-web
* Update / simplify build instructions
* Rename nginx config file to differentiate it from EC config