Move sponsor modal to a generic partial & redesign.

... use for booths also.

app/views/conferences/_tickets.html.haml

@@ -13,13 +13,12 @@
       .row.row-centered
         - @conference.tickets.each do |ticket|
           .col-md-3.col-sm-3.col-centered.col-top
-            %h3.text-center
-              = ticket.title
-            %h3.text-center
-              %i.fa.fa-ticket.fa-3x
-            = markdown(ticket.description)
-            %p.text-center
-              = link_to conference_tickets_path(@conference.short_title),
-                class: 'btn btn-success' do
-                Get Ticket
-                = humanized_money_with_symbol ticket.price
+            = link_to(conference_tickets_path(@conference.short_title),
+              class: 'thumbnail') do
+              .caption
+                %h3.text-center
+                  = ticket.title
+                = markdown(ticket.description)
+                %button.btn-block.btn.btn-lg.btn-success
+                  %i.fa.fa-ticket.fa-fw
+                  = humanized_money_with_symbol(ticket.price)