title: Devise rake db:migrate fails because of duplicate column in my User's table - Rails 3.1
body: <p>This is the error I get when I am first installing Devise and running <code>rake db:migrate</code>:</p>
  
  <pre><code>==  AddDeviseToUsers: migrating ===============================================
  -- change_table(:users)
  rake aborted!
  An error has occurred, this and all later migrations canceled:
  
  SQLite3::SQLException: duplicate column name: email: ALTER TABLE "users" ADD "email" varchar(255) DEFAULT '' NOT NULL
  </code></pre>
  
  <p>Given that this is just test data, I could just delete that column in my db and re-run it, but that doesn't seem very Railsy - if only for the reason that it will making my staging server (the only other server with my app) out-of-sync with my <code>localhost</code>.</p>
  
  <p>Also, what if there is a conflict with another column.</p>
  
  <p>So given that this is the schema of my <code>User</code> table before running the migration, how should I handle this? With a migration of some sort that does a rename?</p>
  
  <pre><code># == Schema Information
  #
  # Table name: users
  #
  #  id         :integer         not null, primary key
  #  email      :string(255)
  #  f_name     :string(255)
  #  l_name     :string(255)
  #  username   :string(255)
  #  role_id    :integer
  #  picture    :string(255)
  #  about_me   :string(255)
  #  website    :string(255)
  #  created_at :datetime
  #  updated_at :datetime
  #
  </code></pre>