DataCollection and Rb::InstanceChooser fixes (more details inside)

* DataCollection.get_parameter_recursive will not join lists into strings
* Fixed Rb::InstanceChooser not to accept a string parameter, only lists
* Fixed a bug where Rb::InstanceChooser didn't handle pointers to lists
  properly
Merge pull request #1 from omribahumi/master

DataCollection and Rb::InstanceChooser fixes (more details inside)