Extract user utility code into own module

This provides more room for expansion, and reduces the amount of
arbitrary code in the __init__.py file for the new package.

app/main/views/agreement.py

@@ -8,7 +8,7 @@ from app.main import main
 from app.main.forms import AcceptAgreementForm
 from app.models.organisation import Organisation
 from app.s3_client.s3_mou_client import get_mou
-from app.utils import user_has_permissions
+from app.utils.user import user_has_permissions
 
 
 @main.route('/services/<uuid:service_id>/agreement')