Separate files needing GPL license

+ Keep apache license for now, until this is completed:
  https://wiki.fd.io/view/TSC/Relicensing_Procedure
+ Add utilities for switching license comment blocks.
 - They do not preserve attributes, so executable flag is lost.
+ Move the affected files to GPL/.
 + Update paths so files are executed from the new location.
 + Change the way scripts are started to do not require executable flag.
 + Employ OptionString when constructing longer command lines.
+ Move also PacketVerifier.py and TrafficScriptArg.py
  as they are linked with traffic scripts.
 + That means the two files are outside "resources" package tree now.
 + Added __init__.py files so relative imports work in new package tree.
+ Start traffic scripts as python modules to allow relative imports.
 + Once again needed because they are outside the default PYTHONPATH.

Change-Id: Ieb135629e890adbaf5b79497570f3be25b746f9f
Signed-off-by: Vratko Polak <vrpolak@cisco.com>