Enable Native Python Types for Jinja2

Helps with #151 (Github Pull Request), but only for Ansible >= 2.7
and when Jinja >= 2.10 is in use.

For other version combinations we still need the workaround proposed
in the pull rqeuest.

ansible.cfg

@@ -1,2 +1,4 @@
 [defaults]
 retry_files_enabled = False
+# jinja2_native helps with problems like https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/151
+jinja2_native = True