An exception was thrown, if no previous version was found. This made it impossible

to configure the plugin in parent projects. An error message is now logged instead.
PR: MOJO-723
Submitted-By: Roland Asmann <Roland.Asmann@cfc.at>


git-svn-id: file:///home/tiste/MOJOHAUS-TO-GIT/SVN-MOJO-WIP/trunk/mojo/clirr-maven-plugin@3809 52ab4f32-60fc-0310-b215-8acea882cd1b