Configuration file for server doesn't allow unexpected values

[TomHellier]

I'm attempting to use this chart with the latest server, and it is expecting different values in the configuration file for the server.

It is currently impossible to use with the current chart as it is difficult to clear maps: helm/helm#5184

I will add ability to fully override the contents of the configuration file

[morremeyer]

@TomHellier You can override with ~ instead of null in current versions of helm to remove a map key.

The server config should allow for arbitrary values, you can add any key you want to .Values.server.config.