xci: Yet another try to find how best to structure stuff

Summary of changes are
- flavors directory has been removed and the flavor config files are
moved into config and renamed to <flavor>-vars
- common files are put under file
- files specific to flavors are put under file/<flavor> directories
- templates and var files are stored in template and var directories
respectively
- 3 playbooks are created

Change-Id: I8a93e0947ccb02f93a6c8f00da27e0cc6b4dc21e
Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>