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/rooms/_form.html.haml

@@ -1,4 +1,15 @@
-= f.input :name
-= f.input :size, :input_html => {:size => 5}
-= f.input :public, :as => :boolean
-= f.action :submit, as: :button, button_html: { class: 'btn btn-primary' }
+.row
+  .col-md-12
+    .page-header
+      %h1
+        - if @room.new_record?
+          New
+        Room
+        = @room.name
+.row
+  .col-md-8
+    = semantic_form_for(@room, :url => (@room.new_record? ? admin_conference_rooms_path : admin_conference_room_path(@conference.short_title, @room))) do |f|
+      = f.input :name
+      = f.input :size, :input_html => {:size => 5}
+      %p.text-right
+        = f.action :submit, as: :button, button_html: { class: 'btn btn-primary' }