Linting Service#cli_transcode

Fix hanging indent and remove ignore line.
Split off decoding from cli_output

Introduces a new private method called _cli_decode() that will handle
the decoding and logging of the returned output.
Extend _cli_exec() to support redirecting stderr

This will be needed for a future call to read stderr from CLI tools.
Introduce cli_output_error() for services

This will allow a service to check the stderr output of a tool and
ignore its return code.