proof of concept for painting timespans

the view-event page demos a limited set of the features of painting dates. 

timeslots are the cells in the calendar that represent dates. they are represented by a css class
timespans are the painted spans that show when someone is available. They are represented by both a css class and a javascript object prototype.

Currently, a user can add dates of various sizes by dragging the mouse on the calendar. They can then move these timespans by dragging the already-created spans. The spans will always "snap" to cover an entire timeslot.