Add invoices views for admin

app/views/admin/invoices/index.haml

@@ -0,0 +1,31 @@
+.row
+  .col-sm-12
+    %h2.text-center-xs= t('invoices')
+%hr
+.row
+  .col-md-12
+    .table-responsive
+      %table.table.table-hover.table-bordered.table-condensed
+        %thead
+          %tr
+            %th{class: 'col-xs-3'}
+              = sort_link(@q, 'invoice')
+            %th{class: 'col-xs-3'}
+              = sort_link(@q, 'buyer')
+            %th{class: 'col-xs-3'}
+              = sort_link(@q, 'due_date')
+            %th{class: 'col-xs-3'}
+              = sort_link(@q, 'receipt_date')
+        %tbody
+          - @invoices.each do |x|
+            %tr
+              %td= link_to(t('invoice_no', no: x.id), [:admin, x])
+              %td= link_to(x.buyer_name, admin_registrar_path(x.buyer_id))
+              %td= l(x.due_date)
+              - if x.binded?
+                %td= l(x.receipt_date)
+              - else
+                %td.text-danger= t('unpaid')
+.row
+  .col-md-12
+    = paginate @invoices

app/views/admin/invoices/show.haml

@@ -0,0 +1,15 @@
+.row
+  .col-sm-6
+    %h1.text-center-xs
+      = t('invoice_no', no: @invoice.id)
+  .col-sm-6
+    %h1.text-right.text-center-xs
+      = link_to(t('back'), :back, class: 'btn btn-default')
+%hr
+.row
+  .col-md-6= render 'registrar/invoices/partials/details'
+.row
+  .col-md-6= render 'registrar/invoices/partials/seller'
+  .col-md-6= render 'registrar/invoices/partials/buyer'
+.row
+  .col-md-12= render 'registrar/invoices/partials/items'