Temporarly for usage of maven-release-plugin 2.5

I want to use git 1.8.5 and the plugin has an issue with this version (see
https://jira.codehaus.org/browse/MRELEASE-812)
[maven-release-plugin] prepare release maven-soapui-extension-plugin-4.6.3.1
[maven-release-plugin] prepare for next development iteration
Fix link to wiki pages
4.6.3.1 has been released
Add support for maven 3.2.1
maven 2.2.1: disable test-multi IT #108

This is a workaround before implementing a working solution. At least, the
build does not fail anymore and we have documented this behaviour