Trigger next Stage on notification events

[ashwanthkumar]

I saw a message on gocd mailing list. The option 3, that I suggested seems like a general pattern which this plugin can support.

Ability to trigger the next stage (if any) on a stage failure or trigger another pipeline on a stage failure. The former one is useful to build post-build jobs like what the person has asked for. The latter one is useful to setup post-run stage as separate pipelines so it doesn't affect the main pipeline flow (assuming it does something bigger).