Provide a dedicated deployment property to set environment variables.

[markpollack]

The deployment property use-spring-application-json will take the application properties defined in the DSL and either set them as a json string under the env-var SPRING_APPLICATION_JSON aka SAJ or set an environment variable for each application property. The problem with this is that using env-vars for an application properties is very delicate so not recommended. That leaves no way to reliably pass in an applications properties and set an environment variable, for example one that might be needed by the application for some reason. A new deployment property that lists environment variables to be explicitly set, independent the use of SAJ should be created.

[sangeetakm]

@markpollack is this issue resolved? i want to pass custom property as environment variable which scdf can use to launch my task. I am using rest endpoint to launch task. is there an option to pass env variable while launching task using rest endpoint?