updated image upload

The problem you're having here is that not labeling the image file correctly. You left description in the "f.file_field", update that to image and that should fixed your problem. Here's the before and after:

  <div class="form-group">
    <%= f.label :image %>
    <%= f.file_field :description, class: "form-control" %>

to 

  <div class="form-group">
    <%= f.label :image %>
    <%= f.file_field :image, class: "form-control" %>