Use the new mmg api

app/clients/sms/mmg.py

@@ -78,8 +78,9 @@ class MMGClient(SmsClient):
         }
 
         start_time = monotonic()
+        mmg_url = "https://api.mmg.co.uk/json/api.php"
         try:
-            response = request("POST", "https://www.mmgrp.co.uk/API/json/api.php",
+            response = request("POST", mmg_url,
                                data=json.dumps(data),
                                headers={'Content-Type': 'application/json',
                                         'Authorization': 'Basic {}'.format(self.api_key)})
@@ -89,7 +90,7 @@ class MMGClient(SmsClient):
             self.current_app.logger.info(
                 "API {} request on {} succeeded with {} '{}'".format(
                     "POST",
-                    "https://www.mmgrp.co.uk/API/json/api.php",
+                    mmg_url,
                     response.status_code,
                     response.json().items()
                 )
@@ -99,7 +100,7 @@ class MMGClient(SmsClient):
             self.current_app.logger.error(
                 "API {} request on {} failed with {} '{}'".format(
                     "POST",
-                    "https://www.mmgrp.co.uk/API/json/api.php",
+                    mmg_url,
                     api_error.status_code,
                     api_error.message
                 )