create base package 'osm_ro_plugin' for plugin

contains base packabe, dummy and failing connectors

All plugins will require this package instead of osm_ro
In that way plugin development is more independent
from main project, and it can be re-used in other projects.
For example openvim can use these SDN plugins without importing osm_ro

Change-Id: I9b598fdca269f04391e731cd07bb244f3918635d
Signed-off-by: tierno <alfonso.tiernosepulveda@telefonica.com>