This solves 414 by adopting new format for config keys and thereby
bypassing the need for case sensitivity in Viper. Also changed
`lookupPluginsInPath` key to `lookup-plugins` and also same for the
persistent flag. The PATH part is implied and can be read from
help.
This is in preparation of introducting eventing and makes sense anyway.
Also, the GVK update handling has been moved to "util" so that it then
can be also reused by eventing.