title: Paperclip for Rails 4 creates NULL records
body: <p>It is taking me all day to config paperclip. I have copied everything from github. I am using devise and rails 4. This is my edit user view, I have added multipart: </p>
  
  <pre><code>&lt;%= form_for(resource, :as =&gt; resource_name, :url =&gt; registration_path(resource_name), :html =&gt; { :method =&gt; :put, :multipart =&gt; true }) do |f| %&gt; 
  &lt;%= f.label 'Add an image' %&gt;
  &lt;%= f.file_field :avatar %&gt;
  </code></pre>
  
  <p>In my show view, I have</p>
  
  <pre><code>&lt;%= image_tag @user.avatar.url %&gt;
  </code></pre>
  
  <p>This shows the default missing image I Set up in user.rb.I cloned <a href="https://github.com/thoughtbot/paperclip_demo" rel="nofollow">paperclip demo</a> and ran it and it works fine on my machine. 
  I installed imagemagick correctly and jpeg decoder.
  This is my user.rb model:</p>
  
  <pre><code>class User &lt; ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :token_authenticatable, :confirmable,
  # :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
       :recoverable, :rememberable, :trackable, :validatable
  attr_accessible :name, :email, :password, :password_confirmation, :remember_me, :avatar
  letsrate_rater
  
  has_attached_file :avatar, :styles =&gt; { :medium =&gt; "300x300&gt;", :thumb =&gt; "50x50&gt;" }, :default_url =&gt; "avatar/missing.jpg"
  
   validates_attachment_content_type :avatar, :content_type =&gt; /\Aimage\/.*\Z/
  
  end
  </code></pre>
  
  <p>and my users_controller.rb:</p>
  
  <pre><code>class UsersController &lt; ApplicationController
  def create
    User.create(user_params)
  end
  private
  def user_params
  params.require(:user).permit(:name, :email, :password, :password_confirmation, :remember_me, :avatar)
  end
  end
  </code></pre>
  
  <p>Also paperclip doesn't create public/avatars and public/system folders and files?
  Help!</p>