[NPANDAY-505] split plugin executables from other executables

The use of the resolver, which in turn needs to use the base executable
factory, caused a circular dependency that works in Maven 3.0+ and fails
in Maven 2.

git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1608808 13f79535-47bb-0310-9956-ffa450edef68