Fixes needed for running tests against puppet's master branch

Specifically this commit

 - Adds specific checks for puppet 3 when loading storeconfig code
   storeconfig does not work against current master and will be removed
   as part of Puppet 4.0.0. We want to maintain backward compatibility,
   so the code supports both

 - Removes references to Puppet[:trusted_node_data] when on Puppet
   4 (essentially assuming it is always true on 4). Like above we will
   look for it when on Puppet 3.y.z and ignore it (assuming true) when
   on Puppet 4.y.z
I liked the use of "feature" because it is an existing concept (as opposed to inventing some other utility method that you have never seen before). And yes, the way it checks if it is 3x or 4x is ugly and due to that we do not keep track of "next release" in source - we simply do not know until it is actually released.