I need the plugin to be able to load artifacts from any upstream build
that eventually triggered this buikd. Not just the direct parent. Added a recursive call to getBuild to make that happen.

Including unit test scenario with a grandparent job which has the artifact that the job wants.
Aligning with origin/master
Encasing in a single block and pulling out a upstream variable
Extending timeouts, since cloudbees is so slow
Merge pull request #18 from quidryan/parentofparent

Clone of spark404's Parent of Parent fix