DockerTask needs more configuration options

[twotired]

For building, I need to be able to specify:

• buildOptions so that I can provide --build-arg and -f path/to/Dockerfile
• pullCretentialsSource

For pushing:

• pushCredentialsSource
• pushRepository

I tried extending DockerTask, but then I couldn't figure out how to add my custom tasks to the job:

No signature of method: ch.mibex.bamboo.plandsl.dsl.tasks.Tasks.leftShift() is applicable for argument types: (null) values: [null]