Test invalid older_than, template_types, and bad ids

Come up with some simple tests in the routes, just to see we get
back what we expect as errors.

app/dao/notifications_dao.py

@@ -8,7 +8,7 @@ from itertools import groupby
 
 from flask import current_app
 from werkzeug.datastructures import MultiDict
-from sqlalchemy import (desc, func, or_, and_, asc, cast, Text)
+from sqlalchemy import (desc, func, or_, and_, asc)
 from sqlalchemy.orm import joinedload
 
 from app import db, create_uuid

app/v2/notifications/get_notifications.py

@@ -1,5 +1,4 @@
 from flask import jsonify, request, url_for
-
 from app import api_user
 from app.dao import notifications_dao
 from app.schema_validation import validate