add add one-off notification status

completely mimicks the job status page, and as such, all the code and
templates have been taken from the job page. This page performs
exactly the same as the job page for now

* total, sending, delivered, failed blue boxes (though they'll just
  read 0/1 for now.
* download report button (same as with job download, except without job
  or row number in file)
* removed references to scheduled
* kept references to help (aka tour/tutorial) as that'll eventually
  change over from a job to a one-off too

app/utils.py

@@ -1,11 +1,13 @@
 import re
 import csv
-from io import StringIO, BytesIO
+from io import StringIO
 from os import path
 from functools import wraps
 import unicodedata
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 
+import dateutil
+import ago
 from flask import (
     abort,
     current_app,
@@ -15,6 +17,11 @@ from flask import (
     url_for
 )
 from flask_login import current_user
+import pyexcel
+import pyexcel.ext.io
+import pyexcel.ext.xls
+import pyexcel.ext.xlsx
+import pyexcel.ext.ods3
 
 from notifications_utils.template import (
     SMSPreviewTemplate,
@@ -23,12 +30,6 @@ from notifications_utils.template import (
     LetterPreviewTemplate,
 )
 
-import pyexcel
-import pyexcel.ext.io
-import pyexcel.ext.xls
-import pyexcel.ext.xlsx
-import pyexcel.ext.ods3
-
 
 SENDING_STATUSES = ['created', 'pending', 'sending']
 DELIVERED_STATUSES = ['delivered', 'sent']
@@ -144,13 +145,31 @@ def generate_notifications_csv(**kwargs):
                 notification['status'],
                 notification['created_at']
             ]
-            line = ','.join([str(i) for i in values]) + '\n'
+            line = ','.join(str(i) for i in values) + '\n'
             yield line
 
         if notifications_resp['links'].get('next'):
             kwargs['page'] += 1
         else:
             return
+    raise Exception("Should never reach here")
+
+
+def generate_single_notification_csv(notification):
+    fieldnames = ['Recipient', 'Template', 'Type', 'Status', 'Time']
+    yield ','.join(fieldnames) + '\n'
+
+    values = [
+        notification['to'],
+        notification['template']['name'],
+        notification['template']['template_type'],
+        notification['status'],
+        notification['created_at']
+    ]
+    line = ','.join(str(i) for i in values) + '\n'
+    yield line
+
+    return
 
 
 def get_page_from_request():
@@ -301,3 +320,16 @@ def get_current_financial_year():
     current_month = int(now.strftime('%-m'))
     current_year = int(now.strftime('%Y'))
     return current_year if current_month > 3 else current_year - 1
+
+
+def get_time_left(created_at):
+    return ago.human(
+        (
+            datetime.now(timezone.utc).replace(hour=23, minute=59, second=59)
+        ) - (
+            dateutil.parser.parse(created_at) + timedelta(days=8)
+        ),
+        future_tense='Data available for {}',
+        past_tense='Data no longer available',  # No-one should ever see this
+        precision=1
+    )