[WIP] added endpoint and dao to create invites for users.

Droped token as later code to send email invite can generate
timebased url to send to user. That can then be checked
against configurable time threshold for expiry. Therefore
no need to store a token.

tests/app/invite/test_invite_rest.py

@@ -0,0 +1,70 @@
+import json
+
+from tests import create_authorization_header
+
+
+def test_create_invited_user(notify_api, sample_service):
+    with notify_api.test_request_context():
+        with notify_api.test_client() as client:
+
+            email_address = 'invited_user@service.gov.uk'
+            invite_from = sample_service.users[0]
+
+            data = {
+                'service': str(sample_service.id),
+                'email_address': email_address,
+                'from_user': invite_from.id
+            }
+
+            data = json.dumps(data)
+
+            auth_header = create_authorization_header(
+                path='/service/{}/invite'.format(sample_service.id),
+                method='POST',
+                request_body=data
+            )
+
+            response = client.post(
+                '/service/{}/invite'.format(sample_service.id),
+                headers=[('Content-Type', 'application/json'), auth_header],
+                data=data
+            )
+            assert response.status_code == 201
+            json_resp = json.loads(response.get_data(as_text=True))
+
+            assert json_resp['data']['service'] == str(sample_service.id)
+            assert json_resp['data']['email_address'] == email_address
+            assert json_resp['data']['from_user'] == invite_from.id
+            assert json_resp['data']['id']
+
+
+def test_create_invited_user_invalid_email(notify_api, sample_service):
+    with notify_api.test_request_context():
+        with notify_api.test_client() as client:
+
+            email_address = 'notanemail'
+            invite_from = sample_service.users[0]
+
+            data = {
+                'service': str(sample_service.id),
+                'email_address': email_address,
+                'from_user': invite_from.id
+            }
+
+            data = json.dumps(data)
+
+            auth_header = create_authorization_header(
+                path='/service/{}/invite'.format(sample_service.id),
+                method='POST',
+                request_body=data
+            )
+
+            response = client.post(
+                '/service/{}/invite'.format(sample_service.id),
+                headers=[('Content-Type', 'application/json'), auth_header],
+                data=data
+            )
+            assert response.status_code == 400
+            json_resp = json.loads(response.get_data(as_text=True))
+            assert json_resp['result'] == 'error'
+            assert json_resp['message'] == {'email_address': ['Invalid email']}