Add table of recipients

Uses an adapted version of the 'summary table' pattern from Digital Marketplace
frontend toolkit:
http://alphagov.github.io/digitalmarketplace-frontend-toolkit/summary-table.html

app/templates/components/placeholder.html

@@ -0,0 +1,3 @@
+{% macro placeholder(variable) %}
+  <span class='placeholder'>{{variable}}</span>
+{% endmacro %}