Created new queries to return the rate with the sum of billable units for the year totals.

Once we have the new columns in notifications table, the query will need to include the rate multiplier and if the number is international.
The monthly billing query will be built next.

tests/app/dao/test_date_utils.py

@@ -0,0 +1,13 @@
+from app.dao.date_util import get_financial_year, get_april_fools
+
+
+def test_get_financial_year():
+    start, end = get_financial_year(2000)
+    assert str(start) == '2000-03-31 23:00:00'
+    assert str(end) == '2001-03-31 23:00:00'
+
+
+def test_get_april_fools():
+    april_fools = get_april_fools(2016)
+    assert str(april_fools) == '2016-03-31 23:00:00'
+    assert april_fools.tzinfo is None