Added photo model

app/models/conference.rb

@@ -42,7 +42,7 @@ class Conference < ActiveRecord::Base
   has_many :vchoices, :dependent => :destroy
   has_many :sponsorship_levels, dependent: :destroy
   has_many :sponsors, dependent: :destroy
-
+  has_many :photos, dependent: :destroy
   belongs_to :venue
 
   accepts_nested_attributes_for :rooms, :reject_if => proc {|r| r["name"].blank?}, :allow_destroy => true

app/models/photo.rb

@@ -0,0 +1,11 @@
+class Photo < ActiveRecord::Base
+  attr_accessible :picture, :description
+  belongs_to :conference
+  validates_presence_of :picture
+  has_attached_file :picture,
+                    styles: { thumb: '100x100>', large: '300x300>' }
+
+  validates_attachment_content_type :picture,
+                                    content_type: [/jpg/, /jpeg/, /png/, /gif/],
+                                    size: { in: 0..500.kilobytes }
+end