SLING-3996 - New maven project wizard should not allow early finish,
before performing serve operations

SetupServerWizardPage is now by default not complete, which forces the
user to visit it before finishing the wizard.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1628993 13f79535-47bb-0310-9956-ffa450edef68