title: DBIx::Class::Schema::Loader: make_schema_at doesn't find any relationship
body: <p>I'm working on a little project in order to learn to use DBIx::Class and
  I'm trying to use DBIx::Class::Schema::Loader to get the the schema code from the database.
  The make_schema_at tool creates the schema, but doesn't insert any relation between the classes.
  There is a how I'm proceding:
  Creating the tables:</p>
  
  <pre><code>CREATE TABLE recipe (
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
      name varchar(255) NOT NULL,
      description TEXT NOT NULL
  )
  ENGINE InnoDB, CHARACTER SET utf8;
  
  CREATE TABLE ingredient(
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
      recipe_id INT NOT NULL REFERENCES recipe(id),
      name TEXT NOT NULL,
      quantity INT NOT NULL
  )
  ENGINE InnoDB, CHARACTER SET utf8;
  </code></pre>
  
  <p>and then:</p>
  
  <pre><code>perl -MDBIx::Class::Schema::Loader=make_schema_at,dump_to_dir:./lib -e 'make_schema_at("Recipes::Schema", { debug =&gt; 1 }, [ "dbi:mysql:dbname=recipes","user", "pass" ])'
  </code></pre>
  
  <p>What I'm doing wrong?
  Thanks in advance.</p>