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/defaults/main.yml b/defaults/main.yml
index d0a5403..41d87ff 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -18,3 +18,7 @@
 ## tftpd config
 # files to copy to the TFTP server
 tftpd_files: []
+
+# Set this to listen on a specific non-default IP address. Only has effect on
+# OpenBSD TFTP server
+# tftpd_listen_ip: 10.0.0.1