[NPANDAY-632] NPE when using netHome maven configuration

Make sure executableConfig is always initialised with a list for
executablePaths before attempting to add netHome to the list

Submitted by: Greg Domjan


git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1610336 13f79535-47bb-0310-9956-ffa450edef68