Include the steps on how to execute the ITs correctly from NPanday trunk

https://npanday.svn.codeplex.com/svn/npanday-its/trunk/ needs to be built and installed first in the local repo (using 'mvn clean install -Prun-ITs') before the ITs can be executed from NPanday source. Otherwise, no tests will be be run.
The relation or difference between https://npanday.svn.codeplex.com/svn/npanday-its/trunk/ and https://npanday.svn.codeplex.com/svn/trunk/npanday-it-runner/ should also be documented to avoid confusion.