Make international SMS on for new services

International SMS is a mature, documented feature now. There’s no reason
it shouldn’t be available to everyone. If it’s turned off by default
then we’re relying on people finding it in the settings page to know
that it exists (which we found in research the other week that users,
who would have benefitted from having international SMS, were failing to
do).

This also fixes the problem whereby users signing up for Notify with an
international phone number (eg those working abroad for the Foreign and
Commonwealth Office) couldn’t get through the tour because they weren’t
able to send themselves the example text message (see
https://www.pivotaltracker.com/story/show/150705515).

tests/app/conftest.py

@@ -137,7 +137,7 @@ def sample_service(
     restricted=False,
     limit=1000,
     email_from=None,
-    permissions=[SMS_TYPE, EMAIL_TYPE],
+    permissions=None,
     research_mode=None,
     free_sms_fragment_limit=250000
 ):
@@ -166,7 +166,7 @@ def sample_service(
         if user not in service.users:
             dao_add_user_to_service(service, user)
 
-    if INBOUND_SMS_TYPE in permissions:
+    if permissions and INBOUND_SMS_TYPE in permissions:
         create_inbound_number('12345', service_id=service.id)
 
     return service