Description:
    Stubs out a new database migration. Pass the migration name, either
    CamelCased or under_scored, and an optional list of attribute pairs as arguments.

    A migration class is generated in db/migrate prefixed by the latest migration number.

    You can name your migration in either of these formats to generate add/remove
    column lines from supplied attributes: AddColumnsToTable or RemoveColumnsFromTable

Example:
    `./script/generate migration AddSslFlag`

    With 4 existing migrations, this creates the AddSslFlag migration in
    db/migrate/005_add_ssl_flag.rb

    `./script/generate migration AddTitleBodyToPost title:string body:text published:boolean`
    
    This will create the AddTitleBodyToPost in db/migrate/005_add_title_body_to_post.rb with
    this in the Up migration:

      add_column :posts, :title, :string  
      add_column :posts, :body, :text  
      add_column :posts, :published, :boolean

    And this in the Down migration:
    
      remove_column :posts, :published  
      remove_column :posts, :body  
      remove_column :posts, :title
