Merge changes from topic "TST009_benchmark"

* changes:
  New PROX commit ID and bug fix
  code review comments and PROX commit ID
  Code review feedback & back-ground traffic support
  Fix run_iteration when not using the sut_sock
  Specify latency bucket size & correct calculation
  Initial support for percentile latency measurements
  Combine code for fixed rate and variable rate tests
  Better Latency accuray warning message
  Support for ETSI GS NFV-TST 009