Refactoring Tickets

- Tickets now independent from registration
- Implemented money gem
#419

app/views/admin/tickets/show.html.haml

@@ -0,0 +1,33 @@
+%h1
+  = @ticket.title
+  %small
+    = humanized_money_with_symbol @ticket.price
+- if @ticket.description.present?
+  %p.lead
+    = markdown(@ticket.description)
+
+%h4 The following persons bought this ticket:
+%table.table#buyers-datatable
+  %thead
+    %th #
+    %th Name
+    %th E-Mail
+    %th Affiliation
+    %th Paid
+  %tbody
+    - @ticket.buyers.each_with_index do |buyer, index|
+      %tr
+        %td
+          = index + 1
+        %td
+          = buyer.name
+          %span.label.label-success
+            = buyer.ticket_purchases.find_by(ticket_id: @ticket.id).quantity
+        %td
+          = buyer.email
+        %td
+          = buyer.affiliation
+        %td
+          = @ticket.paid?(buyer)
+= link_to 'Edit', edit_admin_conference_ticket_path(@conference.short_title, @ticket.id),
+  method: :get, class: 'btn btn-primary'