Add support to Promoted Builds on Build Pipeline Plug-in

From https://code.google.com/p/build-pipeline-plugin/issues/detail?id=80

Jenkins Build Pipeline Plug-in, by Centrum Systems (Australia), is an excellent plug-in, used by many users (over 6000 downloads according to last report).

However, it does not work well with the Jenkins Promoted Builds Plug-in, another great plug-in (over 4100 downloads last month).

It means that users are not able to create pipelines based on promotion (promoted pipelines?). This contribution would be awesome, useful and help a lot of users (maybe over 10000? :-)