The Ultra Music Festival will not return next year to Miami, marking the end of two decades of danceable electronic music presentations by the bayfront in the Magic City.Ultra announced it's farewell in a letter sent Wednesday afternoon, which simultaneously interrupted the festival's long history with the City of Miami.Organizers are now backing off on an agreement that allowed them to hold the most recent event at Virginia Key, a controversial move driven by commissioners who pulled out the Bayfront Park festival in September.Under the contract, Ultra and the...