Refactored EventListing project so the Service classes' add methods take groupId as a parameter

Refactored EventListing project so the Service classes' add methods take groupId as a parameter. Previously, groupId was retrieved from ServiceContext; this works fine except when adding entities via JSON WS. Regenerated services and WSDDs.

Also, refactored project to synchronize method names, variable names, and code formatting between the two portlets.

@sez11a