Allow a job to be scheduled any time in next 96hrs

If you want to send a job on Monday morning, you should be able to
schedule it on Friday. You shouldn’t need to work on the weekend.

96 hours is a full 4 days, so you can schedule a job at any time on
Friday for any time on Monday.

We’ve checked with the information assurance people, and they’re OK
with us holding the data for this extra amount of time.

This commit changes the choose time form from showing one radio button
for each of the next 24 hours to one for each of the next 96 hours. It
changes the labels from ‘9am’ to ‘Monday at 9am’ so it’s clear which
day you’re choosing.

tests/app/main/test_choose_time_form.py

@@ -9,12 +9,28 @@ def test_form_contains_next_24h(app_):
 
     choices = ChooseTimeForm().scheduled_for.choices
 
+    # Friday
     assert choices[0] == ('', 'Now')
-    assert choices[1] == ('2016-01-01T12:00:00.061258', 'Midday')
-    assert choices[23] == ('2016-01-02T10:00:00.061258', '10am')
+    assert choices[1] == ('2016-01-01T12:00:00.061258', 'Today at midday')
+    assert choices[13] == ('2016-01-02T00:00:00.061258', 'Today at midnight')
+
+    # Saturday
+    assert choices[14] == ('2016-01-02T01:00:00.061258', 'Tomorrow at 1am')
+    assert choices[37] == ('2016-01-03T00:00:00.061258', 'Tomorrow at midnight')
+
+    # Sunday
+    assert choices[38] == ('2016-01-03T01:00:00.061258', 'Sunday at 1am')
+
+    # Monday
+    assert choices[84] == ('2016-01-04T23:00:00.061258', 'Monday at 11pm')
+    assert choices[85] == ('2016-01-05T00:00:00.061258', 'Monday at midnight')
 
     with pytest.raises(IndexError):
-        assert choices[24]
+        assert choices[
+            12 +        # hours left in the day
+            (3 * 24) +  # 3 days
+            2           # magic number
+        ]
 
 
 @freeze_time("2016-01-01 11:09:00.061258")