Fix: Include parent pom when building a maven repository

When creating a maven repository, it is necessary to include the parent
pom into the set of artifacts. We therefore include 
org.eclipse:org.eclipse.gemini.dbaccess.parent

Bug https://bugs.eclipse.org/bugs/show_bug.cgi?id=391632

Change-Id: I6d611ceed3c7e3d8b734f5dcda9854a1b4606825
Signed-off-by: Juergen G. Kissner <juergen.kissner@sap.com>