Trace mode is useful for shell code, but less so for golang. Adding debug logging in golang for trigger calls makes it a little easier to see what is happening.
Previously, this could get a bit hazy when running the command within a goroutine. The new method creates pipes for writing stdout/stderr for each call to PluginTriggerOutput, then debug logs if if trace mode is on.
While it is a bit weird to read, it is more correct and should get rid of any parallel processing issues.
The previous output would also include a message like `exit status 1`. This allows us to silence that output and instead only capture that which was return from the subprocess.
