adds administrator to spending proposal

app/views/admin/spending_proposals/edit.html.erb

@@ -1,4 +1,11 @@
 <%= form_for @spending_proposal, url: admin_spending_proposal_path(@spending_proposal) do |f| %>
+
+  <%= f.select :administrator_id,
+               @admins.collect { |a| [ "#{a.name} (#{a.email})", a.id ] },
+               { include_blank: t("admin.spending_proposals.show.undefined"),
+                 label: false },
+               class: "js-submit-on-change" %>
+
   <div class="small-12 column">
     <%= f.label :tag_list, t("proposals.form.tags_label") %>
     <p class="note"><%= t("proposals.form.tags_instructions") %></p>