6.1.x dev guide

Jesse, if you would, please review the changes (last commit) I put into the sections on writing and calling the local service, in the service builder chapter. I'd like to update Liferay.com with these 6.1.x changes to resolve the inconsistency issue spotted out by a reader.

Without, copying in the entire solution EventLocalServiceImpl, I copied it in minus the addResource methods and custom finder method. I think it's good to have the full fledged versions of these classes in the solution, as we'll eventually be using their content (e.g., for permissions and resources sections).

Thanks.