Support for setting hippo:version in initilization to prevent updater execution

If a project contains an updater module, there is no possibility to prevent this updater from being executed by adding a version tag to /hippo:configuration/hippo:initialize/hippo:version.

This is particularly needed for the local development environment; starting up the CMS the second time may lead to errors if the content is already up to date.

A known workaround is to startup with -Drepo.upgrade=false