Fix for excessive growth of sonar.libraries property in complex multiproject setups

In big multiproject setups with a lot of 3rd party dependencies, the sonar.libraries
 property can grow to an extent that hangs the sonar plugin.
This fix avoids this by collecting the source,test and binary folders as well as the libraries in a Set (for each) first and then generating the respective properties from that sets.
It also avoids visiting the same project multiple times which might improve performance as well.

also see http://sonar.15.x6.nabble.com/Sonar-IDE-Local-Analysis-hangs-with-complex-project-setup-td5013238.html