Enable automatic code formatter with CI validation

This may be controversial but it we're doing it. Having code formatting needs to be consistent
and a non-issue during code review. I'm willing modify the configuration if people see a strong
need, but formatting needs to be present and enforced.

src/main/java/org/kohsuke/github/GHQueryBuilder.java

@@ -9,7 +9,7 @@ public abstract class GHQueryBuilder<T> {
     protected final GitHub root;
     protected final Requester req;
 
-    /*package*/ GHQueryBuilder(GitHub root) {
+    /* package */ GHQueryBuilder(GitHub root) {
         this.root = root;
         this.req = root.retrieve();
     }