vpp_config: Rework for Python2/3 compatibility.

On ubuntu:
   $cd <basedir>/extras/vpp_config
   $./scripts/clean.sh
   $./scripts/cp-data.sh
   $sudo apt-get install python3-pip python3-setuptools
   $python3 -m pip install .
   $vpp-config

Changes:
   * Convert to print() function.
   * raw_input changes.
   * floor division changes.
   * replace vpp-config.py with a setuptools 'vpp-config' entry_point.
   * replace netaddr with ipaddress from the standard library and backport.
   * .decode() subprocess.Popen's stdout because in python3 they are bytes.

Change-Id: Id98894ee54e0c31a0ba0304134b159caef415705
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>
diff --git a/extras/vpp_config/vpplib/VppGrubUtil.py b/extras/vpp_config/vpplib/VppGrubUtil.py
index 1723170..d199f1e 100644
--- a/extras/vpp_config/vpplib/VppGrubUtil.py
+++ b/extras/vpp_config/vpplib/VppGrubUtil.py
@@ -101,7 +101,8 @@
         value = cmdline.split('{}='.format(grubcmdline))[1]
         value = value.rstrip('"').lstrip('"')
 
-        # jadfix intel_pstate=disable sometimes cause networks to hang on reboot
+        # jadfix intel_pstate=disable sometimes cause networks to
+        # hang on reboot
         # iommu = re.findall(r'iommu=\w+', value)
         # pstate = re.findall(r'intel_pstate=\w+', value)
         # If there is already some iommu commands set, leave them,