Log an error if detected cdk registry is wrong

This is a followup of JBIDE-24783.
When minishift openshift registry is unable to return a valid registry, the tooling should log an error. JBIDE-24783 was supposed to add this thing (along with removing the default value), but I was not able to trigger the error.

The workflow is:
Once cdk is started in eclipse, the cdk tooling will create the openshift connection and run minishift openshift registry to figure out which registry to use. But in my testing even if this returns "bla bla", the tooling will happily accept it.

To test this, you can use a simple minishift wrapper such as this:

#!/bin/bash

case $* in
"openshift registry")
	echo bla bla
	exit 1
	;;
*)
	/Users/rasp/jbossqa/cdk/cdk-3.1.0/minishift $*
esac

You can also remove the "exit 1" to check what happens with zero exit code.

In my opinion any of these should trigger an error:
a) minishift openshift registry finishes with a non-zero code
b) the returned string is not a valid url