Set application ports feature request

[patrickcrocker]

As reported by @BartoszKaszewczuk in #79 (comment) the ability to set application ports would enable pipeline authors to enable non-default (8080) or multiple application ports for an application.

For implementation reference:

• Configuring CF to Route Traffic to Apps on Custom Ports
• "Multiple App Ports" Demo on Cloud Foundry
• multi-port-app