Add Resource People to Events

[bryanbibat]

Resource People (speakers, instructors, etc) have a many-to-many relationship with Events:

resource_people --< participants >-- events

We need to create a convenient way to link the Resource People with the Events on the Edit Event page. Nested forms are fine.

Once the admin user can create the join table entries, we need to display the list of resource people beside or below the Schedule. The custom titles/descriptions also override their main titles/description just for that event.