configurable origin in loadgen

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
runner passes origin to loadgen

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
don't include child PIDs in CPU usage computation

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>