Refactor usage of Krustlet config to allow using command line parameters to configure agent

[soenkeliebau]

Currently all command line parameters are passed to the Krustlet config code as well, which causes an exception if any parameters are present that the Krustlet does not understand. In reverse, any command line parameters which the agent doesn't unterstand cause an exception in the agent.

The combination of these two means that it is currently not possible to pass anything on the commandline (except maybe version or help) - because for any parameter one of the two components will fail.

This should be fixed by manually constructing a Krustlet config object instead of using the methods that parse the command line, but this requires some boiler plate and re-implementation of default values.