Better handle PowerShell command execution in Bamboo

Issue Summary

Currently, Bamboo is only looking for a successful response code with a PowerShell script. So, by default, if you run a PowerShell script task with some non existing command, Bamboo will mark this task as successful.

Steps to Reproduce

1. Create a script task with powershell interpreter and coma content like "idonotexist"
2. Run the plan

Expected Results

Script task fails

Actual Results

Script task is green even though the above command will cause an error.

Workaround

There's a workaround of handing errors in a PowerShell script, for example, check exit code of commands or/and set $ErrorActionPreference = "Stop"