Fix default value of testng.reportFilenamePattern

The default filename is "testng-results.xml". See https://github.com/cbeust/testng/blob/bd1e7d431b9a108ffe1b42f2976756e4b372cfb3/src/main/java/org/testng/reporters/XMLReporter.java#L29
Merge pull request #12 from juherr/patch-1

Fix default value of testng.reportFilenamePattern