only build addin when appropriate assemblies are in place from VS

git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1609951 13f79535-47bb-0310-9956-ffa450edef68
run ITs on x64 systems as well

git-svn-id: https://svn.apache.org/repos/asf/incubator/npanday/trunk@1609952 13f79535-47bb-0310-9956-ffa450edef68