Extracting Photos form Conference edit form

close #384

app/views/admin/photos/index.html.haml

@@ -0,0 +1,22 @@
+%h1 Photos
+%p.text-muted
+  Photo's will appear in the gallery of the conference splash page.
+- @photos.each_slice(3) do |slice|
+  .row.row-flex.row-flex-wrap
+    - slice.each do |photo|
+      .col-md-4
+        .thumbnail.flex-col
+          %h3.text-center
+            = photo.picture_file_name
+          = image_tag(photo.picture(:large), class: 'img-responsive', title: photo.description)
+          .caption.flex-grow
+          .caption
+            = link_to edit_admin_conference_photo_path(@conference.short_title, photo.id), class: 'btn btn-primary' do
+              %i.fa.fa-pencil-square-o
+                Edit
+            = link_to admin_conference_photo_path(@conference.short_title, photo.id), method: :delete, class: 'btn btn-danger' do
+              %i.fa.fa-times-circle
+                Delete
+.row{'style'=>'padding-top: 10px;'}
+  .col-md-12
+    = link_to 'New Photo', new_admin_conference_photo_path, class: 'btn btn-primary'