title: Rails fixtures get table names wrong
body: <p>I have a <code>roles</code> table, a <code>permissions</code> table, and to join them in a many-to-many relationship a <code>roles_permissions</code> table.</p>
  
  <p>In the <code>roles.yml</code> file I have this:</p>
  
  <pre><code>admin:
    name: admin
    permissions: create_user, edit_user, view_all_users
  </code></pre>
  
  <p>In the <code>permissions.yml</code> I have:</p>
  
  <pre><code>create_user:
    name: create_user
    description: Create a new user
  
  edit_user:
    name: edit_user
    description: Edit any user details
  
  view_all_users:
    name: view_all_users
    description: View all users
  </code></pre>
  
  <p>Now <code>rake test</code> gives me errors saying <code>no such table: permissions_roles: DELETE FROM "permissions_roles"</code></p>
  
  <p>When I comment out the line in <code>roles.yml</code> that specifies the admin permissions then the errors go away.</p>
  
  <p>It looks like the fixtures are assuming the joining table is named <code>permissions_roles</code> when it's actually named <code>roles_permissions</code></p>
  
  <p>How do I tell it the right table name?</p>