[OPENENGSB-3513] made openengsb-root to all projects parent 

http://issues.openengsb.org/jira/browse/OPENENGSB-3513

One question I came up with during the work on this issue: should the domains and the connectors also have root as parent too? I believe that the domain parent and the connector parent make sense because of the whole wsdl, features, assembly stuff.