title: Existing EF migrations became invisible after refactoring
body: <p>I use EF code first migrations in my project. At the moment I've got 2 migrations.
  Tried to create database from scratch but <code>update-database</code> returns an error </p>
  
  <blockquote>
    <p>No migrations configuration type was found in the assembly
    'Project.DAL'</p>
  </blockquote>
  
  <p>On the other hand <code>enable-migrations</code> returns </p>
  
  <blockquote>
    <p>Migrations have already been enabled in project 'Project.DAL'</p>
  </blockquote>
  
  <p>When I started Project I had configuration: <code>Project.Api</code>, <code>Project.Web</code> and <code>Project.Shared</code>(Migrations were here). Then I separated <code>Project.Shared</code> onto <code>Project.BLL</code>, <code>Project.Model</code> and <code>Project.DAL</code>(now Migrations here). Maybe that changes were the reason of current situation.</p>