Test Case for Issue 10

[spina]

I wrote a test case for issue 10. If you go into <gradle_cobertura>/DisabledTestsTest and run 'gradle -x test cobertura' the build will fail. If you run 'gradle cobertura' the build succeeds. I did not hook this test into the root gradle build very well. I would expect the test or check task in the root project to run this test. The test also doesn't get it's dependency from the root correctly-- it pulls a statically defined version of the plugin from the Ivy repo. Would you like me to do more work on this?