Jenkins DSL: enable Github PR builds, it seems to be functional now

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1849885 13f79535-47bb-0310-9956-ffa450edef68

jenkins/create_jobs.groovy

@@ -97,8 +97,7 @@ def poijobs = [
         ],
         [ name: 'POI-DSL-Windows-1.8', trigger: 'H */12 * * *', windows: true, slaves: 'Windows'
         ],
-        [ name: 'POI-DSL-Github-PullRequests', trigger: '', githubpr: true, skipcigame: true,
-                disabled: true // not fully functional yet, thus disable it for now
+        [ name: 'POI-DSL-Github-PullRequests', trigger: '', githubpr: true, skipcigame: true
         ],
 ]