xci: Set up the basics for xci developer sandbox

xci: Set up the basics for xci developer sandbox

This change creates
- initial version of the script to initiate the VM node creation and
provisioning with bifrost and OpenStack installation with openstack-ansible
- pinned-versions to hold the "known working" versions. releng will use master
until the development is complete.
- user-vars to hold user variables
- configuration files to keep settings for different flavors
- ansible files (playbooks, inventory files, variables) per flavor. These
files are empty at the moment in order to save the chosen path makes sense.
Once the way is agreed on, these will be similar to the files listed below
with different content per flavor.
    https://gerrit.opnfv.org/gerrit/gitweb?p=releng.git;a=blob;f=prototypes/openstack-ansible/playbooks/inventory
    https://gerrit.opnfv.org/gerrit/gitweb?p=releng.git;a=blob;f=prototypes/openstack-ansible/playbooks/configure-xcimaster.yml
    https://gerrit.opnfv.org/gerrit/gitweb?p=releng.git;a=blob;f=prototypes/openstack-ansible/var/ubuntu.yml

These new files will be the ones used when the actual deployment is done
with openstack-ansible based on the flavor chosen by developer (or CI).

Change-Id: Ia2f38416a161abd186cbcca61e105c6a68f78b54
Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>