Add events as the associated entity to a project when created in the Events Settings tab

The create/edit project form assumes the project is stand-alone, and provides no interface, graphical or otherwise, to change that assumption.

When the form is loaded as a tab in an event, additional parameters should be passed via the URL to create the association between volunteer project and event. For the 2.0 release, no graphical interface is necessary. URL params need to specify both the entity table and entity id.