Added an unobtrusive way to support triggers. This is necessary in a situation where you don't have control of what your context class inherits from, like Microsoft.AspNet.Identity.EntityFramework.IdentityDbContext<...> which inherits from DbContext. The only functionality lost is a strong-typed reference to the DbContext-derived class in the trigger delegates. As of this commit, there is no reference to a DbContext in the triggers at all. I will add a reference to DbContext next. You'll have to cast it to your derived context class in the trigger body.
Added reference to DbContext back into the trigger delegates, along with a helper method to get your derived context instance.