Allow scheduling volunteers for sessions.

Also fix a small bug for admin registrations edit.

app/views/proposals/show.html.haml

@@ -29,29 +29,20 @@
 
   .row
     .col-md-3
-      %h3
       - if @event.speakers.any?
-        Presented by:
+        %h3
+          Presented by:
         - @speakers_ordered.each do |speaker|
-          .speakerinfo
-            .row
-              .col-md-4
-                = image_tag speaker.profile_picture(:size => 120), class: 'img-responsive img-rounded'
-              .col-md-8
-                %h4
-                  = link_to speaker.name, user_path(speaker.id)
-                  %br
-                  - if speaker.email_public?
-                    = mail_to "#{ speaker.email }" do
-                      %i.fa.fa-envelope-o.fa-2x
-                - if speaker.affiliation?
-                  .text-muted
-                    from
-                    = speaker.affiliation
-            -if speaker.biography?
-              .row.speakerbio
-                .col-md-12
-                  = markdown(speaker.biography)
+          = render 'speaker_info', speaker: speaker
+      / end speakers.
+      - if @event.volunteers.any?
+        %h3
+          Volunteer Hosts
+          %br
+          %small Thanks for helping with #{@conference.title}!
+        - @event.volunteers.each do |volunteer|
+          = render 'volunteer_info', speaker: volunteer, show_bio: false
+
     .col-md-9
       .row
         .col-md-12
@@ -93,9 +84,10 @@
           .col-md-12
             %dt Conference:
             %dd= link_to @event.program.conference.title, conference_path(@conference)
-          .col-md-12
-            %dt Language:
-            %dd= @event.language if @event.language
+          - if @event.language
+            .col-md-12
+              %dt Language:
+              %dd= @event.language
           .col-md-12
             %dt Track:
             %dd