upgrade python2 to python3

Upgrading Django from version 1.9.6 to 2.2.3 because of security issue [1].

Bin Yang passed on the message from the TSC meeting that we need to fix [1] in E release, otherwise, we won’t be able to publish the Plugin.

The last version to support Python 2.7 is Django 1.11 LTS, so we must upgrade Python2 to Python3.

Bin said this is a top priority. He let me fix it for Ocata, Pike and StarlingX plug-in. Other plug-ins are responsible for other plug-in owners.

If we don’t fix [1] for Ocata, Pike and  StarlingX plug-in, those plug-ins will be deleted. we also can’t submit pluggable function.

[1] security issue image which can be found in the attachment.