Improve/fix RFC3442 entries and add tests

- Generate the rfc3442 words using a filter plugin, instead of Jinja
- basic sanity test when running plugin standalone
- Improve testing by creating/binding to a bridge0 interface in
  molecule docker container, then verifying that it's running
- Add ntp option
- multiplatform support

Change-Id: I7c2c3081e8919174dd29b3ab2fdd27b4f6eb843a
diff --git a/vars/Debian.yml b/vars/Debian.yml
index 5a1a5f8..01b6dc6 100644
--- a/vars/Debian.yml
+++ b/vars/Debian.yml
@@ -9,6 +9,7 @@
 
 dhcpd_service: "isc-dhcp-server"
 dhcpd_config_dir: "/etc/dhcp"
+dhcpd_groupname: "root"
 
 tftpd_service: "tftpd-hpa"
 tftpd_groupname: "tftp"