Rework of statistics reporting

Rework of statistics reporting

- Cleanup of the format.yaml file.
- Adding of the packet mis-ordering statistics
- Added a warmup phase to get the correct mis-ordering statistics since
  ARP messages need to be dealt with before we can collect correct
  misordering stats
- Code cleanup avoiding some long lines
- Removing background traffic control from rapid_flowsizetest.py since
  this is already done in the iteration code in rapid_test.py

Change-Id: I4c60a90353f27b8e2d0b62505e8f1cd886a17f0a
Signed-off-by: Luc Provoost <luc.provoost@intel.com>