API Options For Run-As Credentials

[elsastark]

Would like to see more flexible options for workflow run-as credential settings, both for when publishing the workflow and kicking off the job. 

Here is a thread where we discuss the limitations we are seeing when trying to publish the workflow to Gallery via an API. We would also like to see more flexibility when our users want to kick off their workflows via an API where they could pass in different run-as credentials they would like the job to run as.