[UP-4245] exclude logback from the build during the hbm2ddl goal

Calendar portlet is the first portlet to both do db-init and use a logback.xml file.   Unfortunately, the version of the hibernate plugin blows up with that combination.  I could not quickly find a way to pass a system property to the configuration to force it to use the command-line.logback.xml file.   So, for now, just exclude logback from that plugins dependencies.   It still outputs to the console, but no longer fails my build.