Forgot to instantiate nickname property in the constructor
Added connection string to Web.config
Started moving database functionality away from NHibernate; it was proving too difficult to manage with classes that involve multiple joins. Only Team class no longer uses NHibernate (so far).
Fixed a bug in which Team.Equals(Team) would return false even though they were both, in fact, identical.

Also added the User.Nickname property to the equality calculations in User._Equals(User) and User.GetHashCode(), as I had forgotten them before.
Made the cache globally accessible