Addec column live to events

This is so it will show up on the site or elsewhere only when we want it to.
Added site_url column to events
Schema
Shows whether or not event is live on events index view
Coloring live or ntoe liv on events index view
Event#events_by_year can now return all or just live events
Added checkbox for making an event live
Added Site URL to Events edit view
Updated seeds for events agenda and live
Schema
Speakers are now selected in Events edit view
Before save, agenda is saved to YAML string
Replaces speaker ids in agenda to speaker objects
When returning the agenda, turns it from YAML to array of hashes
Added bold to labels in many views
Downcases the email to save to DB
Checks downcased email against DB
If email not in DB, no longer redirects to new user form. That was annoying
Events show view shows sponsors now
Check boxes for sponsors on events edit view