metrics: add reporting for nuttcp test
metrics: add reporting for nuttcp test

Add results reporting for network-metrics-nuttcp.sh via save_results().
Rework data extraction from results files to reduce subshells.

Signed-off-by: Brett T. Warden <3c49f16b9d4a3f688e955241c679cb8951e4845a@intel.com>

chavafg/tests,MarioCarrilloA/tests,sboeuf/tests,devimc/tests,clearcontainers/tests,bwarden/tests,sboeuf/tests,devimc/tests,chavafg/tests,bwarden/tests,MarioCarrilloA/tests,clearcontainers/tests