parse output of health and use double

Change-Id: I3b1d37924164d220fb89b49166563d2fa041e3c4
diff --git a/test-service.groovy b/test-service.groovy
index fb6c274..cf1dcc6 100644
--- a/test-service.groovy
+++ b/test-service.groovy
@@ -86,7 +86,7 @@
             }
 
             writeFile(file: 'report.xml', text: salt.getFileContent(saltMaster, TEST_TEMPEST_TARGET, '/root/report.xml'))
-            junit(keepLongStdio: true, testResults: 'report.xml', healthScaleFactor: TEST_JUNIT_RATIO)
+            junit(keepLongStdio: true, testResults: 'report.xml', healthScaleFactor:  Double.parseDouble(TEST_JUNIT_RATIO))
         }
 
     } catch (Throwable e) {