Switched to using a isinstance check on the string.
Added an order by clause to dao_get_template_usage_stats_by_service, it was causing an itermitten failure in the tests.
similar to sms/email, however, for consistency with response values
and internal storage, rather than supplying an "email_address" field
or a "phone_number" field, supply an "address_line_1" and "postcode"
field within the personalisation object.
