ui: Add ovirt-node-doc

ovirt-node-doc allows easy acces to the python modules/packages related
to ovirt-node.

It can be called like:

$ ovirt-node-doc

to get a high level overview of the modules and packages.
To get more informations about e.g. the installer (whcih resides in the
installer package), the following cmdline can be used:

$ ovirt-node-doc installer

Change-Id: I7db3a965f9c2907c1b8b755b4dec830c4a019d6f
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>