title: Map System.Uri using Entity Framework Fluent Api
body: <p>Pretty simple question.  I have a model that has a property which is a <code>System.Uri</code> type.  <code>Uri</code>s don't have a default parameterless constructor, and no ID field.  Is there any way to override my model generation to store it in the DB in a custom way (e.g. just as a <code>string</code>)? In NHibernate, I've done this before by implementing <code>IUserType</code>, but I could not find yet a similar mechanism in CodeFirst. </p>
  
  <p>Obviously, I could create a custom type that uses a <code>Uri</code> under the hood and exposes regular mappable properties &amp; constructor, I'm just curious if there's any way to map this system type so that I don't have to make a wrapper like that.</p>