title: Adding defaults to integer columns, error saying 'right sytnax near 'default-1 default null'
body: <p>I have a column named 'parent_id' that I am trying to add a default of -1 to:</p>
  
  <pre><code>change_column  :categories, :parent_id, :default =&gt; -1
  </code></pre>
  
  <p>The type is a integer in mysql.</p>
  
  <p>I am getting the error:</p>
  
  <pre><code>'mysql2 error......'default-1 default null' at line 1:
  alter table 'categories' change 'parent_id' 'parent_id' default-1 default null
  </code></pre>
  
  <p>It seems it is missing = sign?</p>
  
  <p>Also, how do I do a db:migrate on the test db?</p>