fix gradle plugin - issue #574 

I fixed issue #574 by switching from properly calls to method calls in case of setters as it cause some problems when setter is overloaded http://jira.codehaus.org/browse/GROOVY-6084

As a bonus I made OsgiLargeTest runnable on different system then windows, handling issue in maven related to coping resource and reserving executable rights. http://jira.codehaus.org/browse/MRESOURCES-132