Implement consistent admin interface

* Consistent route/model/controller/view layout
* Get rid of unused photos, speakers, dietchoices, social_events controllers
* Drop unused :public from Rooms and :description from CallForPapers

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

@@ -1,5 +1,39 @@
 .row
-  .col-md-8
-    = semantic_form_for(@conference, :url => admin_conference_sponsor_path(@conference.short_title, @conference.sponsors)) do |f|
-      = dynamic_association :sponsors, "Sponsors", f
-      = f.action :submit, :as => :button, :button_html => {:class => "btn btn-primary"}
+  .col-md-12
+    .page-header
+      %h1 Sponsors
+      %p.text-muted
+        People supporting your conference
+- if @conference.sponsors.any?
+  .row
+    .col-md-12
+      %table.table.table-hover#sponsors
+        %thead
+          %th Logo
+          %th Name
+          %th Description
+          %th URL
+          %th Level
+          %th Actions
+        %tbody
+          - @conference.sponsors.each do |sponsor|
+            %tr
+              %td
+                = image_tag(sponsor.logo(:thumb), width: '20%')
+              %td
+                = sponsor.name
+              %td
+                = truncate(sponsor.description)
+              %td
+                = sponsor.website_url
+              %td
+                = sponsor.sponsorship_level.title
+              %td
+                .btn-group
+                  = link_to 'Edit', edit_admin_conference_sponsor_path(@conference.short_title, sponsor),
+                  method: :get, class: 'btn btn-primary'
+                  = link_to 'Delete', admin_conference_sponsor_path(@conference.short_title, sponsor),
+                  method: :delete, class: 'btn btn-danger', data: { confirm: "Do you really want to delete the sponsor #{sponsor.name}?" }
+.row
+  .col-md-12
+    = link_to 'Add Sponsor', new_admin_conference_sponsor_path(@conference.short_title), class: 'btn btn-primary pull-right'