This work enables to add vxlan via nmcli module
```
- nmcli:
type: vxlan
conn_name: vxlan_test1
vxlan_id: 16
vxlan_local: 192.168.1.2
vxlan_remote: 192.168.1.5
```
ansible 2.8.0
revision 1: Added tests
Signed-off-by: Susant Sahani <susant@redhat.com>