Mask phone number on jobs page

The phone number on the job page is hard coded at the moment. This is not good
for the demo, and showing it is probably not good because we don’t want to be
storing it forever. So this commit:

- masks it out with bullets • because they’re nicer than asteriks
- adds a ‘row number’ column, which I think is good for users uploading CSVs
  to reconcile the job run with their data (if we’re not showing the data any
  more)

app/templates/views/job.html

@@ -52,19 +52,23 @@
 
     {% call(item) list_table(
       [
-        {'phone': '+447700 900995', 'template': template['name'], 'status': 'queued'}
+        {'row': 1, 'phone': '+447700 900995', 'template': template['name'], 'status': 'queued'}
       ],
       caption=uploaded_file_name,
       caption_visible=False,
       empty_message="Messages go here",
       field_headings=[
+        'Row',
         'Recipient',
         'Template',
         right_aligned_field_heading('Status')
       ]
     ) %}
       {% call field() %}
-        {{item.phone}}
+        {{ item.row }}.
+      {% endcall %}
+      {% call field() %}
+        {{item.phone[:3]}} •••• ••••••
       {% endcall %}
       {% call field() %}
         {{item.template}}