Make main and method responsible for parsing arguments more
modular, so that, it's easier to import them.
Now the argument parser can be imported to an other project,
we want to integrate to. This way, we achieve the CLI which
will be maintained at only one place.
Split main to two parts:
1. arguments handling
2. the rest of config_tempest, which can be importable
as an external module.
Change-Id: I3b1b9cbd05ccdb7ccae1b34211c4c955e831d32d
0f363c03a8