add new template folder

The add new templates page now has option to add template folders.
Tweaked wording of other options and h1 to clarify options since it's
not all about templates any more.

Added api client and stuff for it

app/models/service.py

@@ -8,6 +8,7 @@ from app.notify_client.job_api_client import job_api_client
 from app.notify_client.organisations_api_client import organisations_client
 from app.notify_client.service_api_client import service_api_client
 from app.notify_client.user_api_client import user_api_client
+from app.notify_client.template_folder_client import template_folder_client
 from app.utils import get_default_sms_sender
 
 
@@ -252,3 +253,7 @@ class Service():
     @property
     def has_inbound_number(self):
         return bool(self.inbound_number)
+
+    @cached_property
+    def template_folders(self):
+        return template_folder_client.get_template_folders(self.id)