This commits adds initial support to build Vagrant boxes with the Virtualbox
provider.
- The attribute 'provider' of the option <vagrantconfig> now supports the option
"virtualbox".
- A new boolean attribute 'virtualbox_guest_additions_present' was added to
<vagrantconfig>. When set to true, KIWI will assume that guest additions have
been installed into the base image and configure the shared folders to use
vboxfs, otherwise rsync will be used.
This fixes#532 (https://github.com/SUSE/kiwi/issues/532).
In preparation to support other vagrant providers a base class
for Vagrant operations has been created. Original Code written
by DanČermák <dcermak@suse.com>
The current design of the documentation does not allow for
continous improvement and development. It's missing a basic
structure and concept for documenting step-by-step workflows
and generic explanations.
