update debian packaging

Fixes #29 and the usual setuptools problems, renaming to targetcli-fb and updating to use our -fb versions as dependencies.

The packaging is also changed to use dh_python, rather than all these workarounds. (adding one minor workaround in targetcli-fb.prerm)

Since we don't use lio-utils anymore, I added a init/rc script that loads and mounts configfs and uses targetcli to load and store configurations.

Finally I switched to using Python3.
Note that configshell and rtslib still build Python 2 and Python 3 versions and should keep doing so. Other tools might still use them in Python 2.