Let hosts create event outside of the conference dates

[G0dwin]

Conference hosts should be able to create events that are not part of the official schedule and may fall outside of the official schedule. These events should show as separate entities on the schedule either before or after the schedule table.

An example use case for this would be a post-conference group ride. In 2016 attendees were invited to ride from Guadalajara to Tequila, Detroit has a three day post-conference post conference ride from Detroit to Hell and back.