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/GHReaction.java

@@ -11,14 +11,15 @@ import static org.kohsuke.github.Previews.*;
  * @author Kohsuke Kawaguchi
  * @see Reactable
  */
-@Preview @Deprecated
+@Preview
+@Deprecated
 public class GHReaction extends GHObject {
     private GitHub root;
 
     private GHUser user;
     private ReactionContent content;
 
-    /*package*/ GHReaction wrap(GitHub root) {
+    /* package */ GHReaction wrap(GitHub root) {
         this.root = root;
         user.wrapUp(root);
         return this;
@@ -50,6 +51,6 @@ public class GHReaction extends GHObject {
      * Removes this reaction.
      */
     public void delete() throws IOException {
-        new Requester(root).method("DELETE").withPreview(SQUIRREL_GIRL).to("/reactions/"+id);
+        new Requester(root).method("DELETE").withPreview(SQUIRREL_GIRL).to("/reactions/" + id);
     }
 }