Port to python 3

Port code to python 3 yet remain backward compatible to python 2.
This port is in preparation for yocto 2.4 upgrade.

Partially resolves openbmc/openbmc#2920

Change-Id: If174ce9444bde4e21fb086764f4def017e423201
Signed-off-by: CamVan Nguyen <ctnguyen@us.ibm.com>
7 files changed